multi_buffer.rs

   1mod anchor;
   2#[cfg(test)]
   3mod multi_buffer_tests;
   4mod path_key;
   5mod transaction;
   6
   7use self::transaction::History;
   8
   9pub use anchor::{Anchor, AnchorRangeExt};
  10
  11use anyhow::{Result, anyhow};
  12use buffer_diff::{
  13    BufferDiff, BufferDiffEvent, BufferDiffSnapshot, DiffChanged, DiffHunkSecondaryStatus,
  14    DiffHunkStatus, DiffHunkStatusKind,
  15};
  16use clock::ReplicaId;
  17use collections::{BTreeMap, Bound, HashMap, HashSet};
  18use gpui::{App, Context, Entity, EntityId, EventEmitter};
  19use itertools::Itertools;
  20use language::{
  21    AutoindentMode, BracketMatch, Buffer, BufferChunks, BufferRow, BufferSnapshot, Capability,
  22    CharClassifier, CharKind, CharScopeContext, Chunk, CursorShape, DiagnosticEntryRef, File,
  23    IndentGuideSettings, IndentSize, Language, LanguageScope, OffsetRangeExt, OffsetUtf16, Outline,
  24    OutlineItem, Point, PointUtf16, Selection, TextDimension, TextObject, ToOffset as _,
  25    ToPoint as _, TransactionId, TreeSitterOptions, Unclipped,
  26    language_settings::{LanguageSettings, language_settings},
  27};
  28
  29#[cfg(any(test, feature = "test-support"))]
  30use gpui::AppContext as _;
  31
  32use rope::DimensionPair;
  33use smallvec::SmallVec;
  34use smol::future::yield_now;
  35use std::{
  36    any::type_name,
  37    borrow::Cow,
  38    cell::{Cell, OnceCell, Ref, RefCell},
  39    cmp, fmt,
  40    future::Future,
  41    io,
  42    iter::{self, FromIterator},
  43    mem,
  44    ops::{self, Add, AddAssign, ControlFlow, Range, RangeBounds, Sub, SubAssign},
  45    rc::Rc,
  46    str,
  47    sync::{Arc, OnceLock},
  48    time::Duration,
  49};
  50use sum_tree::{Bias, Cursor, Dimension, Dimensions, SumTree, TreeMap};
  51use text::{
  52    BufferId, Edit, LineIndent, TextSummary,
  53    locator::Locator,
  54    subscription::{Subscription, Topic},
  55};
  56use theme::SyntaxTheme;
  57use util::post_inc;
  58use ztracing::instrument;
  59
  60pub use self::path_key::{PathExcerptInsertResult, PathKey};
  61
  62pub static EXCERPT_CONTEXT_LINES: OnceLock<fn(&App) -> u32> = OnceLock::new();
  63
  64pub fn excerpt_context_lines(cx: &App) -> u32 {
  65    EXCERPT_CONTEXT_LINES.get().map(|f| f(cx)).unwrap_or(2)
  66}
  67
  68#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
  69pub struct ExcerptId(u32);
  70
  71/// One or more [`Buffers`](Buffer) being edited in a single view.
  72///
  73/// See <https://zed.dev/features#multi-buffers>
  74pub struct MultiBuffer {
  75    /// A snapshot of the [`Excerpt`]s in the MultiBuffer.
  76    /// Use [`MultiBuffer::snapshot`] to get a up-to-date snapshot.
  77    snapshot: RefCell<MultiBufferSnapshot>,
  78    /// Contains the state of the buffers being edited
  79    buffers: BTreeMap<BufferId, BufferState>,
  80    /// Mapping from path keys to their excerpts.
  81    excerpts_by_path: BTreeMap<PathKey, Vec<ExcerptId>>,
  82    /// Mapping from excerpt IDs to their path key.
  83    paths_by_excerpt: HashMap<ExcerptId, PathKey>,
  84    /// Mapping from buffer IDs to their diff states
  85    diffs: HashMap<BufferId, DiffState>,
  86    subscriptions: Topic<MultiBufferOffset>,
  87    /// If true, the multi-buffer only contains a single [`Buffer`] and a single [`Excerpt`]
  88    singleton: bool,
  89    /// The history of the multi-buffer.
  90    history: History,
  91    /// The explicit title of the multi-buffer.
  92    /// If `None`, it will be derived from the underlying path or content.
  93    title: Option<String>,
  94    /// The writing capability of the multi-buffer.
  95    capability: Capability,
  96    buffer_changed_since_sync: Rc<Cell<bool>>,
  97}
  98
  99#[derive(Clone, Debug, PartialEq, Eq)]
 100pub enum Event {
 101    ExcerptsAdded {
 102        buffer: Entity<Buffer>,
 103        predecessor: ExcerptId,
 104        excerpts: Vec<(ExcerptId, ExcerptRange<language::Anchor>)>,
 105    },
 106    ExcerptsRemoved {
 107        ids: Vec<ExcerptId>,
 108        /// Contains only buffer IDs for which all excerpts have been removed.
 109        /// Buffers that still have remaining excerpts are never included.
 110        removed_buffer_ids: Vec<BufferId>,
 111    },
 112    ExcerptsExpanded {
 113        ids: Vec<ExcerptId>,
 114    },
 115    ExcerptsEdited {
 116        excerpt_ids: Vec<ExcerptId>,
 117        buffer_ids: Vec<BufferId>,
 118    },
 119    DiffHunksToggled,
 120    Edited {
 121        edited_buffer: Option<Entity<Buffer>>,
 122    },
 123    TransactionUndone {
 124        transaction_id: TransactionId,
 125    },
 126    Reloaded,
 127    LanguageChanged(BufferId, bool),
 128    Reparsed(BufferId),
 129    Saved,
 130    FileHandleChanged,
 131    DirtyChanged,
 132    DiagnosticsUpdated,
 133    BufferDiffChanged,
 134}
 135
 136/// A diff hunk, representing a range of consequent lines in a multibuffer.
 137#[derive(Debug, Clone, PartialEq, Eq)]
 138pub struct MultiBufferDiffHunk {
 139    /// The row range in the multibuffer where this diff hunk appears.
 140    pub row_range: Range<MultiBufferRow>,
 141    /// The buffer ID that this hunk belongs to.
 142    pub buffer_id: BufferId,
 143    /// The range of the underlying buffer that this hunk corresponds to.
 144    pub buffer_range: Range<text::Anchor>,
 145    /// The excerpt that contains the diff hunk.
 146    pub excerpt_id: ExcerptId,
 147    /// The range within the buffer's diff base that this hunk corresponds to.
 148    pub diff_base_byte_range: Range<BufferOffset>,
 149    /// The status of this hunk (added/modified/deleted and secondary status).
 150    pub status: DiffHunkStatus,
 151    /// The word diffs for this hunk.
 152    pub word_diffs: Vec<Range<MultiBufferOffset>>,
 153}
 154
 155impl MultiBufferDiffHunk {
 156    pub fn status(&self) -> DiffHunkStatus {
 157        self.status
 158    }
 159
 160    pub fn is_created_file(&self) -> bool {
 161        self.diff_base_byte_range == (BufferOffset(0)..BufferOffset(0))
 162            && self.buffer_range.start.is_min()
 163            && self.buffer_range.end.is_max()
 164    }
 165
 166    pub fn multi_buffer_range(&self) -> Range<Anchor> {
 167        let start = Anchor::in_buffer(self.excerpt_id, self.buffer_range.start);
 168        let end = Anchor::in_buffer(self.excerpt_id, self.buffer_range.end);
 169        start..end
 170    }
 171}
 172
 173pub type MultiBufferPoint = Point;
 174type ExcerptOffset = ExcerptDimension<MultiBufferOffset>;
 175type ExcerptPoint = ExcerptDimension<Point>;
 176
 177#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 178#[serde(transparent)]
 179pub struct MultiBufferRow(pub u32);
 180
 181impl MultiBufferRow {
 182    pub const MIN: Self = Self(0);
 183    pub const MAX: Self = Self(u32::MAX);
 184}
 185
 186impl ops::Add<usize> for MultiBufferRow {
 187    type Output = Self;
 188
 189    fn add(self, rhs: usize) -> Self::Output {
 190        MultiBufferRow(self.0 + rhs as u32)
 191    }
 192}
 193
 194pub trait MultiBufferDimension: 'static + Copy + Default + std::fmt::Debug {
 195    type TextDimension: TextDimension;
 196    fn from_summary(summary: &MBTextSummary) -> Self;
 197
 198    fn add_text_dim(&mut self, summary: &Self::TextDimension);
 199
 200    fn add_mb_text_summary(&mut self, summary: &MBTextSummary);
 201}
 202
 203// todo(lw): MultiBufferPoint
 204impl MultiBufferDimension for Point {
 205    type TextDimension = Point;
 206    fn from_summary(summary: &MBTextSummary) -> Self {
 207        summary.lines
 208    }
 209
 210    fn add_text_dim(&mut self, other: &Self::TextDimension) {
 211        *self += *other;
 212    }
 213
 214    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 215        *self += summary.lines;
 216    }
 217}
 218
 219// todo(lw): MultiBufferPointUtf16
 220impl MultiBufferDimension for PointUtf16 {
 221    type TextDimension = PointUtf16;
 222    fn from_summary(summary: &MBTextSummary) -> Self {
 223        summary.lines_utf16()
 224    }
 225
 226    fn add_text_dim(&mut self, other: &Self::TextDimension) {
 227        *self += *other;
 228    }
 229
 230    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 231        *self += summary.lines_utf16();
 232    }
 233}
 234
 235#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 236pub struct MultiBufferOffset(pub usize);
 237
 238impl fmt::Display for MultiBufferOffset {
 239    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 240        write!(f, "{}", self.0)
 241    }
 242}
 243
 244impl rand::distr::uniform::SampleUniform for MultiBufferOffset {
 245    type Sampler = MultiBufferOffsetUniformSampler;
 246}
 247
 248pub struct MultiBufferOffsetUniformSampler {
 249    sampler: rand::distr::uniform::UniformUsize,
 250}
 251
 252impl rand::distr::uniform::UniformSampler for MultiBufferOffsetUniformSampler {
 253    type X = MultiBufferOffset;
 254
 255    fn new<B1, B2>(low_b: B1, high_b: B2) -> Result<Self, rand::distr::uniform::Error>
 256    where
 257        B1: rand::distr::uniform::SampleBorrow<Self::X> + Sized,
 258        B2: rand::distr::uniform::SampleBorrow<Self::X> + Sized,
 259    {
 260        let low = *low_b.borrow();
 261        let high = *high_b.borrow();
 262        let sampler = rand::distr::uniform::UniformUsize::new(low.0, high.0);
 263        sampler.map(|sampler| MultiBufferOffsetUniformSampler { sampler })
 264    }
 265
 266    #[inline] // if the range is constant, this helps LLVM to do the
 267    // calculations at compile-time.
 268    fn new_inclusive<B1, B2>(low_b: B1, high_b: B2) -> Result<Self, rand::distr::uniform::Error>
 269    where
 270        B1: rand::distr::uniform::SampleBorrow<Self::X> + Sized,
 271        B2: rand::distr::uniform::SampleBorrow<Self::X> + Sized,
 272    {
 273        let low = *low_b.borrow();
 274        let high = *high_b.borrow();
 275        let sampler = rand::distr::uniform::UniformUsize::new_inclusive(low.0, high.0);
 276        sampler.map(|sampler| MultiBufferOffsetUniformSampler { sampler })
 277    }
 278
 279    fn sample<R: rand::Rng + ?Sized>(&self, rng: &mut R) -> Self::X {
 280        MultiBufferOffset(self.sampler.sample(rng))
 281    }
 282}
 283impl MultiBufferDimension for MultiBufferOffset {
 284    type TextDimension = usize;
 285    fn from_summary(summary: &MBTextSummary) -> Self {
 286        summary.len
 287    }
 288
 289    fn add_text_dim(&mut self, other: &Self::TextDimension) {
 290        self.0 += *other;
 291    }
 292
 293    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 294        *self += summary.len;
 295    }
 296}
 297impl MultiBufferDimension for MultiBufferOffsetUtf16 {
 298    type TextDimension = OffsetUtf16;
 299    fn from_summary(summary: &MBTextSummary) -> Self {
 300        MultiBufferOffsetUtf16(summary.len_utf16)
 301    }
 302
 303    fn add_text_dim(&mut self, other: &Self::TextDimension) {
 304        self.0 += *other;
 305    }
 306
 307    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 308        self.0 += summary.len_utf16;
 309    }
 310}
 311
 312#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq, Hash, serde::Deserialize)]
 313pub struct BufferOffset(pub usize);
 314
 315impl TextDimension for BufferOffset {
 316    fn from_text_summary(summary: &TextSummary) -> Self {
 317        BufferOffset(usize::from_text_summary(summary))
 318    }
 319    fn from_chunk(chunk: rope::ChunkSlice) -> Self {
 320        BufferOffset(usize::from_chunk(chunk))
 321    }
 322    fn add_assign(&mut self, other: &Self) {
 323        TextDimension::add_assign(&mut self.0, &other.0);
 324    }
 325}
 326impl<'a> sum_tree::Dimension<'a, rope::ChunkSummary> for BufferOffset {
 327    fn zero(cx: ()) -> Self {
 328        BufferOffset(<usize as sum_tree::Dimension<'a, rope::ChunkSummary>>::zero(cx))
 329    }
 330
 331    fn add_summary(&mut self, summary: &'a rope::ChunkSummary, cx: ()) {
 332        usize::add_summary(&mut self.0, summary, cx);
 333    }
 334}
 335
 336impl Sub for BufferOffset {
 337    type Output = usize;
 338
 339    fn sub(self, other: BufferOffset) -> Self::Output {
 340        self.0 - other.0
 341    }
 342}
 343
 344impl AddAssign<DimensionPair<usize, Point>> for BufferOffset {
 345    fn add_assign(&mut self, other: DimensionPair<usize, Point>) {
 346        self.0 += other.key;
 347    }
 348}
 349
 350impl language::ToPoint for BufferOffset {
 351    fn to_point(&self, snapshot: &text::BufferSnapshot) -> Point {
 352        self.0.to_point(snapshot)
 353    }
 354}
 355
 356impl language::ToPointUtf16 for BufferOffset {
 357    fn to_point_utf16(&self, snapshot: &text::BufferSnapshot) -> PointUtf16 {
 358        self.0.to_point_utf16(snapshot)
 359    }
 360}
 361
 362impl language::ToOffset for BufferOffset {
 363    fn to_offset(&self, snapshot: &text::BufferSnapshot) -> usize {
 364        self.0.to_offset(snapshot)
 365    }
 366}
 367
 368impl language::ToOffsetUtf16 for BufferOffset {
 369    fn to_offset_utf16(&self, snapshot: &text::BufferSnapshot) -> OffsetUtf16 {
 370        self.0.to_offset_utf16(snapshot)
 371    }
 372}
 373
 374#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
 375pub struct MultiBufferOffsetUtf16(pub OffsetUtf16);
 376
 377impl ops::Add<usize> for MultiBufferOffsetUtf16 {
 378    type Output = MultiBufferOffsetUtf16;
 379
 380    fn add(self, rhs: usize) -> Self::Output {
 381        MultiBufferOffsetUtf16(OffsetUtf16(self.0.0 + rhs))
 382    }
 383}
 384
 385impl ops::Add<OffsetUtf16> for MultiBufferOffsetUtf16 {
 386    type Output = Self;
 387
 388    fn add(self, rhs: OffsetUtf16) -> Self::Output {
 389        MultiBufferOffsetUtf16(self.0 + rhs)
 390    }
 391}
 392
 393impl AddAssign<OffsetUtf16> for MultiBufferOffsetUtf16 {
 394    fn add_assign(&mut self, rhs: OffsetUtf16) {
 395        self.0 += rhs;
 396    }
 397}
 398
 399impl AddAssign<usize> for MultiBufferOffsetUtf16 {
 400    fn add_assign(&mut self, rhs: usize) {
 401        self.0.0 += rhs;
 402    }
 403}
 404
 405impl Sub for MultiBufferOffsetUtf16 {
 406    type Output = OffsetUtf16;
 407
 408    fn sub(self, other: MultiBufferOffsetUtf16) -> Self::Output {
 409        self.0 - other.0
 410    }
 411}
 412
 413impl Sub<OffsetUtf16> for MultiBufferOffsetUtf16 {
 414    type Output = MultiBufferOffsetUtf16;
 415
 416    fn sub(self, other: OffsetUtf16) -> Self::Output {
 417        MultiBufferOffsetUtf16(self.0 - other)
 418    }
 419}
 420
 421#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
 422pub struct BufferOffsetUtf16(pub OffsetUtf16);
 423
 424impl MultiBufferOffset {
 425    const ZERO: Self = Self(0);
 426    pub fn saturating_sub(self, other: MultiBufferOffset) -> usize {
 427        self.0.saturating_sub(other.0)
 428    }
 429    pub fn saturating_sub_usize(self, other: usize) -> MultiBufferOffset {
 430        MultiBufferOffset(self.0.saturating_sub(other))
 431    }
 432}
 433
 434impl ops::Sub for MultiBufferOffset {
 435    type Output = usize;
 436
 437    fn sub(self, other: MultiBufferOffset) -> Self::Output {
 438        self.0 - other.0
 439    }
 440}
 441
 442impl ops::Sub<usize> for MultiBufferOffset {
 443    type Output = Self;
 444
 445    fn sub(self, other: usize) -> Self::Output {
 446        MultiBufferOffset(self.0 - other)
 447    }
 448}
 449
 450impl ops::SubAssign<usize> for MultiBufferOffset {
 451    fn sub_assign(&mut self, other: usize) {
 452        self.0 -= other;
 453    }
 454}
 455
 456impl ops::Add<usize> for BufferOffset {
 457    type Output = Self;
 458
 459    fn add(self, rhs: usize) -> Self::Output {
 460        BufferOffset(self.0 + rhs)
 461    }
 462}
 463
 464impl ops::AddAssign<usize> for BufferOffset {
 465    fn add_assign(&mut self, other: usize) {
 466        self.0 += other;
 467    }
 468}
 469
 470impl ops::Add<usize> for MultiBufferOffset {
 471    type Output = Self;
 472
 473    fn add(self, rhs: usize) -> Self::Output {
 474        MultiBufferOffset(self.0 + rhs)
 475    }
 476}
 477
 478impl ops::AddAssign<usize> for MultiBufferOffset {
 479    fn add_assign(&mut self, other: usize) {
 480        self.0 += other;
 481    }
 482}
 483
 484impl ops::Add<isize> for MultiBufferOffset {
 485    type Output = Self;
 486
 487    fn add(self, rhs: isize) -> Self::Output {
 488        MultiBufferOffset((self.0 as isize + rhs) as usize)
 489    }
 490}
 491
 492impl ops::Add for MultiBufferOffset {
 493    type Output = Self;
 494
 495    fn add(self, rhs: MultiBufferOffset) -> Self::Output {
 496        MultiBufferOffset(self.0 + rhs.0)
 497    }
 498}
 499
 500impl ops::AddAssign<MultiBufferOffset> for MultiBufferOffset {
 501    fn add_assign(&mut self, other: MultiBufferOffset) {
 502        self.0 += other.0;
 503    }
 504}
 505
 506pub trait ToOffset: 'static + fmt::Debug {
 507    fn to_offset(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset;
 508    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16;
 509}
 510
 511pub trait ToPoint: 'static + fmt::Debug {
 512    fn to_point(&self, snapshot: &MultiBufferSnapshot) -> Point;
 513    fn to_point_utf16(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16;
 514}
 515
 516struct BufferState {
 517    buffer: Entity<Buffer>,
 518    last_version: RefCell<clock::Global>,
 519    last_non_text_state_update_count: Cell<usize>,
 520    // Note, any changes to this field value require updating snapshot.buffer_locators as well
 521    excerpts: Vec<Locator>,
 522    _subscriptions: [gpui::Subscription; 2],
 523}
 524
 525struct DiffState {
 526    diff: Entity<BufferDiff>,
 527    main_buffer: Option<Entity<language::Buffer>>,
 528    _subscription: gpui::Subscription,
 529}
 530
 531impl DiffState {
 532    fn snapshot(&self, cx: &App) -> DiffStateSnapshot {
 533        DiffStateSnapshot {
 534            diff: self.diff.read(cx).snapshot(cx),
 535            main_buffer: self.main_buffer.as_ref().map(|b| b.read(cx).snapshot()),
 536        }
 537    }
 538}
 539
 540#[derive(Clone)]
 541struct DiffStateSnapshot {
 542    diff: BufferDiffSnapshot,
 543    main_buffer: Option<language::BufferSnapshot>,
 544}
 545
 546impl std::ops::Deref for DiffStateSnapshot {
 547    type Target = BufferDiffSnapshot;
 548
 549    fn deref(&self) -> &Self::Target {
 550        &self.diff
 551    }
 552}
 553
 554impl DiffState {
 555    fn new(diff: Entity<BufferDiff>, cx: &mut Context<MultiBuffer>) -> Self {
 556        DiffState {
 557            _subscription: cx.subscribe(&diff, |this, diff, event, cx| match event {
 558                BufferDiffEvent::DiffChanged(DiffChanged {
 559                    changed_range,
 560                    base_text_changed_range: _,
 561                    extended_range,
 562                }) => {
 563                    let use_extended = this.snapshot.borrow().use_extended_diff_range;
 564                    let range = if use_extended {
 565                        extended_range.clone()
 566                    } else {
 567                        changed_range.clone()
 568                    };
 569                    if let Some(range) = range {
 570                        this.buffer_diff_changed(diff, range, cx)
 571                    }
 572                    cx.emit(Event::BufferDiffChanged);
 573                }
 574                BufferDiffEvent::LanguageChanged => this.buffer_diff_language_changed(diff, cx),
 575                _ => {}
 576            }),
 577            diff,
 578            main_buffer: None,
 579        }
 580    }
 581
 582    fn new_inverted(
 583        diff: Entity<BufferDiff>,
 584        main_buffer: Entity<language::Buffer>,
 585        cx: &mut Context<MultiBuffer>,
 586    ) -> Self {
 587        let weak_main_buffer = main_buffer.downgrade();
 588        DiffState {
 589            _subscription: cx.subscribe(&diff, {
 590                move |this, diff, event, cx| {
 591                    let Some(main_buffer) = weak_main_buffer.upgrade() else {
 592                        return;
 593                    };
 594                    match event {
 595                        BufferDiffEvent::DiffChanged(DiffChanged {
 596                            changed_range: _,
 597                            base_text_changed_range,
 598                            extended_range: _,
 599                        }) => {
 600                            this.inverted_buffer_diff_changed(
 601                                diff,
 602                                main_buffer,
 603                                base_text_changed_range.clone(),
 604                                cx,
 605                            );
 606                            cx.emit(Event::BufferDiffChanged);
 607                        }
 608                        BufferDiffEvent::LanguageChanged => {
 609                            this.inverted_buffer_diff_language_changed(diff, main_buffer, cx)
 610                        }
 611                        _ => {}
 612                    }
 613                }
 614            }),
 615            diff,
 616            main_buffer: Some(main_buffer),
 617        }
 618    }
 619}
 620
 621/// The contents of a [`MultiBuffer`] at a single point in time.
 622#[derive(Clone, Default)]
 623pub struct MultiBufferSnapshot {
 624    excerpts: SumTree<Excerpt>,
 625    buffer_locators: TreeMap<BufferId, Arc<[Locator]>>,
 626    diffs: TreeMap<BufferId, DiffStateSnapshot>,
 627    diff_transforms: SumTree<DiffTransform>,
 628    excerpt_ids: SumTree<ExcerptIdMapping>,
 629    replaced_excerpts: Arc<HashMap<ExcerptId, ExcerptId>>,
 630    non_text_state_update_count: usize,
 631    edit_count: usize,
 632    is_dirty: bool,
 633    has_deleted_file: bool,
 634    has_conflict: bool,
 635    has_inverted_diff: bool,
 636    singleton: bool,
 637    trailing_excerpt_update_count: usize,
 638    all_diff_hunks_expanded: bool,
 639    show_deleted_hunks: bool,
 640    use_extended_diff_range: bool,
 641    show_headers: bool,
 642}
 643
 644// follower: None
 645// - BufferContent(Some)
 646// - BufferContent(None)
 647// - DeletedHunk
 648//
 649// follower: Some
 650// - BufferContent(Some)
 651// - BufferContent(None)
 652
 653#[derive(Debug, Clone)]
 654enum DiffTransform {
 655    // RealText
 656    BufferContent {
 657        summary: MBTextSummary,
 658        // modified_hunk_info
 659        inserted_hunk_info: Option<DiffTransformHunkInfo>,
 660    },
 661    // ExpandedHunkText
 662    DeletedHunk {
 663        summary: TextSummary,
 664        buffer_id: BufferId,
 665        hunk_info: DiffTransformHunkInfo,
 666        base_text_byte_range: Range<usize>,
 667        has_trailing_newline: bool,
 668    },
 669}
 670
 671#[derive(Clone, Copy, Debug)]
 672struct DiffTransformHunkInfo {
 673    excerpt_id: ExcerptId,
 674    hunk_start_anchor: text::Anchor,
 675    hunk_secondary_status: DiffHunkSecondaryStatus,
 676    is_logically_deleted: bool,
 677}
 678
 679impl Eq for DiffTransformHunkInfo {}
 680
 681impl PartialEq for DiffTransformHunkInfo {
 682    fn eq(&self, other: &DiffTransformHunkInfo) -> bool {
 683        self.excerpt_id == other.excerpt_id && self.hunk_start_anchor == other.hunk_start_anchor
 684    }
 685}
 686
 687impl std::hash::Hash for DiffTransformHunkInfo {
 688    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 689        self.excerpt_id.hash(state);
 690        self.hunk_start_anchor.hash(state);
 691    }
 692}
 693
 694#[derive(Clone)]
 695pub struct ExcerptInfo {
 696    pub id: ExcerptId,
 697    pub buffer: Arc<BufferSnapshot>,
 698    pub buffer_id: BufferId,
 699    pub range: ExcerptRange<text::Anchor>,
 700    pub end_row: MultiBufferRow,
 701}
 702
 703impl std::fmt::Debug for ExcerptInfo {
 704    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 705        f.debug_struct(type_name::<Self>())
 706            .field("id", &self.id)
 707            .field("buffer_id", &self.buffer_id)
 708            .field("path", &self.buffer.file().map(|f| f.path()))
 709            .field("range", &self.range)
 710            .finish()
 711    }
 712}
 713
 714/// A boundary between `Excerpt`s in a [`MultiBuffer`]
 715#[derive(Debug)]
 716pub struct ExcerptBoundary {
 717    pub prev: Option<ExcerptInfo>,
 718    pub next: ExcerptInfo,
 719    /// The row in the `MultiBuffer` where the boundary is located
 720    pub row: MultiBufferRow,
 721}
 722
 723impl ExcerptBoundary {
 724    pub fn starts_new_buffer(&self) -> bool {
 725        match (self.prev.as_ref(), &self.next) {
 726            (None, _) => true,
 727            (Some(prev), next) => prev.buffer_id != next.buffer_id,
 728        }
 729    }
 730}
 731
 732#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 733pub struct ExpandInfo {
 734    pub direction: ExpandExcerptDirection,
 735    pub excerpt_id: ExcerptId,
 736}
 737
 738#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 739pub struct RowInfo {
 740    pub buffer_id: Option<BufferId>,
 741    pub buffer_row: Option<u32>,
 742    pub multibuffer_row: Option<MultiBufferRow>,
 743    pub diff_status: Option<buffer_diff::DiffHunkStatus>,
 744    pub expand_info: Option<ExpandInfo>,
 745    pub wrapped_buffer_row: Option<u32>,
 746}
 747
 748/// A slice into a [`Buffer`] that is being edited in a [`MultiBuffer`].
 749#[derive(Clone)]
 750struct Excerpt {
 751    /// The unique identifier for this excerpt
 752    id: ExcerptId,
 753    /// The location of the excerpt in the [`MultiBuffer`]
 754    locator: Locator,
 755    /// The buffer being excerpted
 756    buffer_id: BufferId,
 757    /// A snapshot of the buffer being excerpted
 758    buffer: Arc<BufferSnapshot>,
 759    /// The range of the buffer to be shown in the excerpt
 760    range: ExcerptRange<text::Anchor>,
 761    /// The last row in the excerpted slice of the buffer
 762    max_buffer_row: BufferRow,
 763    /// A summary of the text in the excerpt
 764    text_summary: TextSummary,
 765    has_trailing_newline: bool,
 766}
 767
 768/// A public view into an `Excerpt` in a [`MultiBuffer`].
 769///
 770/// Contains methods for getting the [`Buffer`] of the excerpt,
 771/// as well as mapping offsets to/from buffer and multibuffer coordinates.
 772#[derive(Clone)]
 773pub struct MultiBufferExcerpt<'a> {
 774    excerpt: &'a Excerpt,
 775    diff_transforms:
 776        sum_tree::Cursor<'a, 'static, DiffTransform, DiffTransforms<MultiBufferOffset>>,
 777    /// The offset in the multibuffer considering diff transforms.
 778    offset: MultiBufferOffset,
 779    /// The offset in the multibuffer without diff transforms.
 780    excerpt_offset: ExcerptOffset,
 781    buffer_offset: BufferOffset,
 782}
 783
 784#[derive(Clone, Debug)]
 785struct ExcerptIdMapping {
 786    id: ExcerptId,
 787    locator: Locator,
 788}
 789
 790/// A range of text from a single [`Buffer`], to be shown as an `Excerpt`.
 791/// These ranges are relative to the buffer itself
 792#[derive(Clone, Debug, Eq, PartialEq, Hash)]
 793pub struct ExcerptRange<T> {
 794    /// The full range of text to be shown in the excerpt.
 795    pub context: Range<T>,
 796    /// The primary range of text to be highlighted in the excerpt.
 797    /// In a multi-buffer search, this would be the text that matched the search
 798    pub primary: Range<T>,
 799}
 800
 801impl<T: Clone> ExcerptRange<T> {
 802    pub fn new(context: Range<T>) -> Self {
 803        Self {
 804            context: context.clone(),
 805            primary: context,
 806        }
 807    }
 808}
 809
 810#[derive(Clone, Debug, Default)]
 811pub struct ExcerptSummary {
 812    excerpt_id: ExcerptId,
 813    /// The location of the last [`Excerpt`] being summarized
 814    excerpt_locator: Locator,
 815    widest_line_number: u32,
 816    text: MBTextSummary,
 817    count: usize,
 818}
 819
 820#[derive(Debug, Clone)]
 821pub struct DiffTransformSummary {
 822    input: MBTextSummary,
 823    output: MBTextSummary,
 824}
 825
 826/// Summary of a string of text.
 827#[derive(Copy, Clone, Debug, Default, Eq, PartialEq)]
 828pub struct MBTextSummary {
 829    /// Length in bytes.
 830    pub len: MultiBufferOffset,
 831    /// Length in UTF-8.
 832    pub chars: usize,
 833    /// Length in UTF-16 code units
 834    pub len_utf16: OffsetUtf16,
 835    /// A point representing the number of lines and the length of the last line.
 836    ///
 837    /// In other words, it marks the point after the last byte in the text, (if
 838    /// EOF was a character, this would be its position).
 839    pub lines: Point,
 840    /// How many `char`s are in the first line
 841    pub first_line_chars: u32,
 842    /// How many `char`s are in the last line
 843    pub last_line_chars: u32,
 844    /// How many UTF-16 code units are in the last line
 845    pub last_line_len_utf16: u32,
 846    /// The row idx of the longest row
 847    pub longest_row: u32,
 848    /// How many `char`s are in the longest row
 849    pub longest_row_chars: u32,
 850}
 851
 852impl From<TextSummary> for MBTextSummary {
 853    fn from(summary: TextSummary) -> Self {
 854        MBTextSummary {
 855            len: MultiBufferOffset(summary.len),
 856            chars: summary.chars,
 857            len_utf16: summary.len_utf16,
 858            lines: summary.lines,
 859            first_line_chars: summary.first_line_chars,
 860            last_line_chars: summary.last_line_chars,
 861            last_line_len_utf16: summary.last_line_len_utf16,
 862            longest_row: summary.longest_row,
 863            longest_row_chars: summary.longest_row_chars,
 864        }
 865    }
 866}
 867
 868impl From<MBTextSummary> for TextSummary {
 869    fn from(summary: MBTextSummary) -> Self {
 870        TextSummary {
 871            len: summary.len.0,
 872            chars: summary.chars,
 873            len_utf16: summary.len_utf16,
 874            lines: summary.lines,
 875            first_line_chars: summary.first_line_chars,
 876            last_line_chars: summary.last_line_chars,
 877            last_line_len_utf16: summary.last_line_len_utf16,
 878            longest_row: summary.longest_row,
 879            longest_row_chars: summary.longest_row_chars,
 880        }
 881    }
 882}
 883
 884impl From<&str> for MBTextSummary {
 885    fn from(text: &str) -> Self {
 886        MBTextSummary::from(TextSummary::from(text))
 887    }
 888}
 889
 890impl MultiBufferDimension for MBTextSummary {
 891    type TextDimension = TextSummary;
 892
 893    fn from_summary(summary: &MBTextSummary) -> Self {
 894        *summary
 895    }
 896
 897    fn add_text_dim(&mut self, summary: &Self::TextDimension) {
 898        *self += *summary;
 899    }
 900
 901    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 902        *self += *summary;
 903    }
 904}
 905
 906impl AddAssign for MBTextSummary {
 907    fn add_assign(&mut self, other: MBTextSummary) {
 908        let joined_chars = self.last_line_chars + other.first_line_chars;
 909        if joined_chars > self.longest_row_chars {
 910            self.longest_row = self.lines.row;
 911            self.longest_row_chars = joined_chars;
 912        }
 913        if other.longest_row_chars > self.longest_row_chars {
 914            self.longest_row = self.lines.row + other.longest_row;
 915            self.longest_row_chars = other.longest_row_chars;
 916        }
 917
 918        if self.lines.row == 0 {
 919            self.first_line_chars += other.first_line_chars;
 920        }
 921
 922        if other.lines.row == 0 {
 923            self.last_line_chars += other.first_line_chars;
 924            self.last_line_len_utf16 += other.last_line_len_utf16;
 925        } else {
 926            self.last_line_chars = other.last_line_chars;
 927            self.last_line_len_utf16 = other.last_line_len_utf16;
 928        }
 929
 930        self.chars += other.chars;
 931        self.len += other.len;
 932        self.len_utf16 += other.len_utf16;
 933        self.lines += other.lines;
 934    }
 935}
 936
 937impl AddAssign<TextSummary> for MBTextSummary {
 938    fn add_assign(&mut self, other: TextSummary) {
 939        *self += MBTextSummary::from(other);
 940    }
 941}
 942
 943impl MBTextSummary {
 944    pub fn lines_utf16(&self) -> PointUtf16 {
 945        PointUtf16 {
 946            row: self.lines.row,
 947            column: self.last_line_len_utf16,
 948        }
 949    }
 950}
 951
 952impl<K, V> MultiBufferDimension for DimensionPair<K, V>
 953where
 954    K: MultiBufferDimension,
 955    V: MultiBufferDimension,
 956{
 957    type TextDimension = DimensionPair<K::TextDimension, V::TextDimension>;
 958
 959    fn from_summary(summary: &MBTextSummary) -> Self {
 960        Self {
 961            key: K::from_summary(summary),
 962            value: Some(V::from_summary(summary)),
 963        }
 964    }
 965
 966    fn add_text_dim(&mut self, summary: &Self::TextDimension) {
 967        self.key.add_text_dim(&summary.key);
 968        if let Some(value) = &mut self.value {
 969            if let Some(other_value) = summary.value.as_ref() {
 970                value.add_text_dim(other_value);
 971            }
 972        }
 973    }
 974
 975    fn add_mb_text_summary(&mut self, summary: &MBTextSummary) {
 976        self.key.add_mb_text_summary(summary);
 977        if let Some(value) = &mut self.value {
 978            value.add_mb_text_summary(summary);
 979        }
 980    }
 981}
 982
 983#[derive(Clone)]
 984pub struct MultiBufferRows<'a> {
 985    point: Point,
 986    is_empty: bool,
 987    is_singleton: bool,
 988    cursor: MultiBufferCursor<'a, Point, Point>,
 989}
 990
 991pub struct MultiBufferChunks<'a> {
 992    excerpts: Cursor<'a, 'static, Excerpt, ExcerptOffset>,
 993    diff_transforms:
 994        Cursor<'a, 'static, DiffTransform, Dimensions<MultiBufferOffset, ExcerptOffset>>,
 995    diffs: &'a TreeMap<BufferId, DiffStateSnapshot>,
 996    diff_base_chunks: Option<(BufferId, BufferChunks<'a>)>,
 997    buffer_chunk: Option<Chunk<'a>>,
 998    range: Range<MultiBufferOffset>,
 999    excerpt_offset_range: Range<ExcerptOffset>,
1000    excerpt_chunks: Option<ExcerptChunks<'a>>,
1001    language_aware: bool,
1002}
1003
1004pub struct ReversedMultiBufferChunks<'a> {
1005    cursor: MultiBufferCursor<'a, MultiBufferOffset, BufferOffset>,
1006    current_chunks: Option<rope::Chunks<'a>>,
1007    start: MultiBufferOffset,
1008    offset: MultiBufferOffset,
1009}
1010
1011pub struct MultiBufferBytes<'a> {
1012    range: Range<MultiBufferOffset>,
1013    cursor: MultiBufferCursor<'a, MultiBufferOffset, BufferOffset>,
1014    excerpt_bytes: Option<text::Bytes<'a>>,
1015    has_trailing_newline: bool,
1016    chunk: &'a [u8],
1017}
1018
1019pub struct ReversedMultiBufferBytes<'a> {
1020    range: Range<MultiBufferOffset>,
1021    chunks: ReversedMultiBufferChunks<'a>,
1022    chunk: &'a [u8],
1023}
1024
1025#[derive(Clone)]
1026struct DiffTransforms<MBD> {
1027    output_dimension: OutputDimension<MBD>,
1028    excerpt_dimension: ExcerptDimension<MBD>,
1029}
1030
1031impl<'a, MBD: MultiBufferDimension> Dimension<'a, DiffTransformSummary> for DiffTransforms<MBD> {
1032    fn zero(cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>) -> Self {
1033        Self {
1034            output_dimension: OutputDimension::zero(cx),
1035            excerpt_dimension: <ExcerptDimension<MBD> as Dimension<'a, DiffTransformSummary>>::zero(
1036                cx,
1037            ),
1038        }
1039    }
1040
1041    fn add_summary(
1042        &mut self,
1043        summary: &'a DiffTransformSummary,
1044        cx: <DiffTransformSummary as sum_tree::Summary>::Context<'_>,
1045    ) {
1046        self.output_dimension.add_summary(summary, cx);
1047        self.excerpt_dimension.add_summary(summary, cx);
1048    }
1049}
1050
1051#[derive(Clone)]
1052struct MultiBufferCursor<'a, MBD, BD> {
1053    excerpts: Cursor<'a, 'static, Excerpt, ExcerptDimension<MBD>>,
1054    diff_transforms: Cursor<'a, 'static, DiffTransform, DiffTransforms<MBD>>,
1055    diffs: &'a TreeMap<BufferId, DiffStateSnapshot>,
1056    cached_region: OnceCell<Option<MultiBufferRegion<'a, MBD, BD>>>,
1057}
1058
1059#[derive(Clone)]
1060struct MultiBufferRegion<'a, MBD, BD> {
1061    buffer: &'a BufferSnapshot,
1062    is_main_buffer: bool,
1063    diff_hunk_status: Option<DiffHunkStatus>,
1064    excerpt: &'a Excerpt,
1065    buffer_range: Range<BD>,
1066    range: Range<MBD>,
1067    has_trailing_newline: bool,
1068}
1069
1070struct ExcerptChunks<'a> {
1071    excerpt_id: ExcerptId,
1072    content_chunks: BufferChunks<'a>,
1073    has_footer: bool,
1074}
1075
1076#[derive(Debug)]
1077struct BufferEdit {
1078    range: Range<BufferOffset>,
1079    new_text: Arc<str>,
1080    is_insertion: bool,
1081    original_indent_column: Option<u32>,
1082    excerpt_id: ExcerptId,
1083}
1084
1085#[derive(Clone, Copy, Debug, PartialEq)]
1086enum DiffChangeKind {
1087    BufferEdited,
1088    DiffUpdated { base_changed: bool },
1089    ExpandOrCollapseHunks { expand: bool },
1090}
1091
1092#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1093pub enum ExpandExcerptDirection {
1094    Up,
1095    Down,
1096    UpAndDown,
1097}
1098
1099impl ExpandExcerptDirection {
1100    pub fn should_expand_up(&self) -> bool {
1101        match self {
1102            ExpandExcerptDirection::Up => true,
1103            ExpandExcerptDirection::Down => false,
1104            ExpandExcerptDirection::UpAndDown => true,
1105        }
1106    }
1107
1108    pub fn should_expand_down(&self) -> bool {
1109        match self {
1110            ExpandExcerptDirection::Up => false,
1111            ExpandExcerptDirection::Down => true,
1112            ExpandExcerptDirection::UpAndDown => true,
1113        }
1114    }
1115}
1116
1117#[derive(Clone, Debug, PartialEq)]
1118pub struct IndentGuide {
1119    pub buffer_id: BufferId,
1120    pub start_row: MultiBufferRow,
1121    pub end_row: MultiBufferRow,
1122    pub depth: u32,
1123    pub tab_size: u32,
1124    pub settings: IndentGuideSettings,
1125}
1126
1127impl IndentGuide {
1128    pub fn indent_level(&self) -> u32 {
1129        self.depth * self.tab_size
1130    }
1131}
1132
1133impl MultiBuffer {
1134    pub fn new(capability: Capability) -> Self {
1135        Self::new_(
1136            capability,
1137            MultiBufferSnapshot {
1138                show_headers: true,
1139                show_deleted_hunks: true,
1140                ..MultiBufferSnapshot::default()
1141            },
1142        )
1143    }
1144
1145    pub fn without_headers(capability: Capability) -> Self {
1146        Self::new_(
1147            capability,
1148            MultiBufferSnapshot {
1149                show_deleted_hunks: true,
1150                ..MultiBufferSnapshot::default()
1151            },
1152        )
1153    }
1154
1155    pub fn singleton(buffer: Entity<Buffer>, cx: &mut Context<Self>) -> Self {
1156        let mut this = Self::new_(
1157            buffer.read(cx).capability(),
1158            MultiBufferSnapshot {
1159                singleton: true,
1160                show_deleted_hunks: true,
1161                ..MultiBufferSnapshot::default()
1162            },
1163        );
1164        this.singleton = true;
1165        this.set_excerpts_for_path(
1166            PathKey::sorted(0),
1167            buffer.clone(),
1168            [Point::zero()..buffer.read(cx).max_point()],
1169            0,
1170            cx,
1171        );
1172        this
1173    }
1174
1175    #[inline]
1176    pub fn new_(capability: Capability, snapshot: MultiBufferSnapshot) -> Self {
1177        Self {
1178            snapshot: RefCell::new(snapshot),
1179            buffers: Default::default(),
1180            diffs: HashMap::default(),
1181            subscriptions: Topic::default(),
1182            singleton: false,
1183            capability,
1184            title: None,
1185            excerpts_by_path: Default::default(),
1186            paths_by_excerpt: Default::default(),
1187            buffer_changed_since_sync: Default::default(),
1188            history: History::default(),
1189        }
1190    }
1191
1192    pub fn clone(&self, new_cx: &mut Context<Self>) -> Self {
1193        let mut buffers = BTreeMap::default();
1194        let buffer_changed_since_sync = Rc::new(Cell::new(false));
1195        for (buffer_id, buffer_state) in self.buffers.iter() {
1196            buffer_state.buffer.update(new_cx, |buffer, _| {
1197                buffer.record_changes(Rc::downgrade(&buffer_changed_since_sync));
1198            });
1199            buffers.insert(
1200                *buffer_id,
1201                BufferState {
1202                    buffer: buffer_state.buffer.clone(),
1203                    last_version: buffer_state.last_version.clone(),
1204                    last_non_text_state_update_count: buffer_state
1205                        .last_non_text_state_update_count
1206                        .clone(),
1207                    excerpts: buffer_state.excerpts.clone(),
1208                    _subscriptions: [
1209                        new_cx.observe(&buffer_state.buffer, |_, _, cx| cx.notify()),
1210                        new_cx.subscribe(&buffer_state.buffer, Self::on_buffer_event),
1211                    ],
1212                },
1213            );
1214        }
1215        let mut diff_bases = HashMap::default();
1216        for (buffer_id, diff) in self.diffs.iter() {
1217            diff_bases.insert(*buffer_id, DiffState::new(diff.diff.clone(), new_cx));
1218        }
1219        Self {
1220            snapshot: RefCell::new(self.snapshot.borrow().clone()),
1221            buffers,
1222            excerpts_by_path: Default::default(),
1223            paths_by_excerpt: Default::default(),
1224            diffs: diff_bases,
1225            subscriptions: Default::default(),
1226            singleton: self.singleton,
1227            capability: self.capability,
1228            history: self.history.clone(),
1229            title: self.title.clone(),
1230            buffer_changed_since_sync,
1231        }
1232    }
1233
1234    pub fn set_group_interval(&mut self, group_interval: Duration) {
1235        self.history.set_group_interval(group_interval);
1236    }
1237
1238    pub fn with_title(mut self, title: String) -> Self {
1239        self.title = Some(title);
1240        self
1241    }
1242
1243    pub fn read_only(&self) -> bool {
1244        !self.capability.editable()
1245    }
1246
1247    pub fn capability(&self) -> Capability {
1248        self.capability
1249    }
1250
1251    /// Returns an up-to-date snapshot of the MultiBuffer.
1252    #[ztracing::instrument(skip_all)]
1253    pub fn snapshot(&self, cx: &App) -> MultiBufferSnapshot {
1254        self.sync(cx);
1255        self.snapshot.borrow().clone()
1256    }
1257
1258    pub fn read(&self, cx: &App) -> Ref<'_, MultiBufferSnapshot> {
1259        self.sync(cx);
1260        self.snapshot.borrow()
1261    }
1262
1263    pub fn as_singleton(&self) -> Option<Entity<Buffer>> {
1264        if self.singleton {
1265            Some(self.buffers.values().next().unwrap().buffer.clone())
1266        } else {
1267            None
1268        }
1269    }
1270
1271    pub fn is_singleton(&self) -> bool {
1272        self.singleton
1273    }
1274
1275    pub fn subscribe(&mut self) -> Subscription<MultiBufferOffset> {
1276        self.subscriptions.subscribe()
1277    }
1278
1279    pub fn is_dirty(&self, cx: &App) -> bool {
1280        self.read(cx).is_dirty()
1281    }
1282
1283    pub fn has_deleted_file(&self, cx: &App) -> bool {
1284        self.read(cx).has_deleted_file()
1285    }
1286
1287    pub fn has_conflict(&self, cx: &App) -> bool {
1288        self.read(cx).has_conflict()
1289    }
1290
1291    // The `is_empty` signature doesn't match what clippy expects
1292    #[allow(clippy::len_without_is_empty)]
1293    pub fn len(&self, cx: &App) -> MultiBufferOffset {
1294        self.read(cx).len()
1295    }
1296
1297    pub fn is_empty(&self) -> bool {
1298        self.buffers.is_empty()
1299    }
1300
1301    pub fn edit<I, S, T>(
1302        &mut self,
1303        edits: I,
1304        autoindent_mode: Option<AutoindentMode>,
1305        cx: &mut Context<Self>,
1306    ) where
1307        I: IntoIterator<Item = (Range<S>, T)>,
1308        S: ToOffset,
1309        T: Into<Arc<str>>,
1310    {
1311        self.edit_internal(edits, autoindent_mode, true, cx);
1312    }
1313
1314    pub fn edit_non_coalesce<I, S, T>(
1315        &mut self,
1316        edits: I,
1317        autoindent_mode: Option<AutoindentMode>,
1318        cx: &mut Context<Self>,
1319    ) where
1320        I: IntoIterator<Item = (Range<S>, T)>,
1321        S: ToOffset,
1322        T: Into<Arc<str>>,
1323    {
1324        self.edit_internal(edits, autoindent_mode, false, cx);
1325    }
1326
1327    fn edit_internal<I, S, T>(
1328        &mut self,
1329        edits: I,
1330        autoindent_mode: Option<AutoindentMode>,
1331        coalesce_adjacent: bool,
1332        cx: &mut Context<Self>,
1333    ) where
1334        I: IntoIterator<Item = (Range<S>, T)>,
1335        S: ToOffset,
1336        T: Into<Arc<str>>,
1337    {
1338        if self.read_only() || self.buffers.is_empty() {
1339            return;
1340        }
1341        self.sync_mut(cx);
1342        let edits = edits
1343            .into_iter()
1344            .map(|(range, new_text)| {
1345                let mut range = range.start.to_offset(self.snapshot.get_mut())
1346                    ..range.end.to_offset(self.snapshot.get_mut());
1347                if range.start > range.end {
1348                    mem::swap(&mut range.start, &mut range.end);
1349                }
1350                (range, new_text.into())
1351            })
1352            .collect::<Vec<_>>();
1353
1354        return edit_internal(self, edits, autoindent_mode, coalesce_adjacent, cx);
1355
1356        // Non-generic part of edit, hoisted out to avoid blowing up LLVM IR.
1357        fn edit_internal(
1358            this: &mut MultiBuffer,
1359            edits: Vec<(Range<MultiBufferOffset>, Arc<str>)>,
1360            mut autoindent_mode: Option<AutoindentMode>,
1361            coalesce_adjacent: bool,
1362            cx: &mut Context<MultiBuffer>,
1363        ) {
1364            let original_indent_columns = match &mut autoindent_mode {
1365                Some(AutoindentMode::Block {
1366                    original_indent_columns,
1367                }) => mem::take(original_indent_columns),
1368                _ => Default::default(),
1369            };
1370
1371            let (buffer_edits, edited_excerpt_ids) = MultiBuffer::convert_edits_to_buffer_edits(
1372                edits,
1373                this.snapshot.get_mut(),
1374                &original_indent_columns,
1375            );
1376
1377            let mut buffer_ids = Vec::with_capacity(buffer_edits.len());
1378            for (buffer_id, mut edits) in buffer_edits {
1379                buffer_ids.push(buffer_id);
1380                edits.sort_by_key(|edit| edit.range.start);
1381                this.buffers[&buffer_id].buffer.update(cx, |buffer, cx| {
1382                    let mut edits = edits.into_iter().peekable();
1383                    let mut insertions = Vec::new();
1384                    let mut original_indent_columns = Vec::new();
1385                    let mut deletions = Vec::new();
1386                    let empty_str: Arc<str> = Arc::default();
1387                    while let Some(BufferEdit {
1388                        mut range,
1389                        mut new_text,
1390                        mut is_insertion,
1391                        original_indent_column,
1392                        excerpt_id,
1393                    }) = edits.next()
1394                    {
1395                        while let Some(BufferEdit {
1396                            range: next_range,
1397                            is_insertion: next_is_insertion,
1398                            new_text: next_new_text,
1399                            excerpt_id: next_excerpt_id,
1400                            ..
1401                        }) = edits.peek()
1402                        {
1403                            let should_coalesce = if coalesce_adjacent {
1404                                range.end >= next_range.start
1405                            } else {
1406                                range.end > next_range.start
1407                            };
1408
1409                            if should_coalesce {
1410                                range.end = cmp::max(next_range.end, range.end);
1411                                is_insertion |= *next_is_insertion;
1412                                if excerpt_id == *next_excerpt_id {
1413                                    new_text = format!("{new_text}{next_new_text}").into();
1414                                }
1415                                edits.next();
1416                            } else {
1417                                break;
1418                            }
1419                        }
1420
1421                        if is_insertion {
1422                            original_indent_columns.push(original_indent_column);
1423                            insertions.push((
1424                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
1425                                new_text.clone(),
1426                            ));
1427                        } else if !range.is_empty() {
1428                            deletions.push((
1429                                buffer.anchor_before(range.start)..buffer.anchor_before(range.end),
1430                                empty_str.clone(),
1431                            ));
1432                        }
1433                    }
1434
1435                    let deletion_autoindent_mode =
1436                        if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
1437                            Some(AutoindentMode::Block {
1438                                original_indent_columns: Default::default(),
1439                            })
1440                        } else {
1441                            autoindent_mode.clone()
1442                        };
1443                    let insertion_autoindent_mode =
1444                        if let Some(AutoindentMode::Block { .. }) = autoindent_mode {
1445                            Some(AutoindentMode::Block {
1446                                original_indent_columns,
1447                            })
1448                        } else {
1449                            autoindent_mode.clone()
1450                        };
1451
1452                    if coalesce_adjacent {
1453                        buffer.edit(deletions, deletion_autoindent_mode, cx);
1454                        buffer.edit(insertions, insertion_autoindent_mode, cx);
1455                    } else {
1456                        buffer.edit_non_coalesce(deletions, deletion_autoindent_mode, cx);
1457                        buffer.edit_non_coalesce(insertions, insertion_autoindent_mode, cx);
1458                    }
1459                })
1460            }
1461
1462            cx.emit(Event::ExcerptsEdited {
1463                excerpt_ids: edited_excerpt_ids,
1464                buffer_ids,
1465            });
1466        }
1467    }
1468
1469    fn convert_edits_to_buffer_edits(
1470        edits: Vec<(Range<MultiBufferOffset>, Arc<str>)>,
1471        snapshot: &MultiBufferSnapshot,
1472        original_indent_columns: &[Option<u32>],
1473    ) -> (HashMap<BufferId, Vec<BufferEdit>>, Vec<ExcerptId>) {
1474        let mut buffer_edits: HashMap<BufferId, Vec<BufferEdit>> = Default::default();
1475        let mut edited_excerpt_ids = Vec::new();
1476        let mut cursor = snapshot.cursor::<MultiBufferOffset, BufferOffset>();
1477        for (ix, (range, new_text)) in edits.into_iter().enumerate() {
1478            let original_indent_column = original_indent_columns.get(ix).copied().flatten();
1479
1480            cursor.seek(&range.start);
1481            let mut start_region = cursor.region().expect("start offset out of bounds");
1482            if !start_region.is_main_buffer {
1483                cursor.next();
1484                if let Some(region) = cursor.region() {
1485                    start_region = region;
1486                } else {
1487                    continue;
1488                }
1489            }
1490
1491            if range.end < start_region.range.start {
1492                continue;
1493            }
1494
1495            let start_region = start_region.clone();
1496            if range.end > start_region.range.end {
1497                cursor.seek_forward(&range.end);
1498            }
1499            let mut end_region = cursor.region().expect("end offset out of bounds");
1500            if !end_region.is_main_buffer {
1501                cursor.prev();
1502                if let Some(region) = cursor.region() {
1503                    end_region = region;
1504                } else {
1505                    continue;
1506                }
1507            }
1508
1509            if range.start > end_region.range.end {
1510                continue;
1511            }
1512
1513            let start_overshoot = range.start.saturating_sub(start_region.range.start);
1514            let end_overshoot = range.end.saturating_sub(end_region.range.start);
1515            let buffer_start = (start_region.buffer_range.start + start_overshoot)
1516                .min(start_region.buffer_range.end);
1517            let buffer_end =
1518                (end_region.buffer_range.start + end_overshoot).min(end_region.buffer_range.end);
1519
1520            if start_region.excerpt.id == end_region.excerpt.id {
1521                if start_region.buffer.capability == Capability::ReadWrite
1522                    && start_region.is_main_buffer
1523                {
1524                    edited_excerpt_ids.push(start_region.excerpt.id);
1525                    buffer_edits
1526                        .entry(start_region.buffer.remote_id())
1527                        .or_default()
1528                        .push(BufferEdit {
1529                            range: buffer_start..buffer_end,
1530                            new_text,
1531                            is_insertion: true,
1532                            original_indent_column,
1533                            excerpt_id: start_region.excerpt.id,
1534                        });
1535                }
1536            } else {
1537                let start_excerpt_range = buffer_start..start_region.buffer_range.end;
1538                let end_excerpt_range = end_region.buffer_range.start..buffer_end;
1539                if start_region.buffer.capability == Capability::ReadWrite
1540                    && start_region.is_main_buffer
1541                {
1542                    edited_excerpt_ids.push(start_region.excerpt.id);
1543                    buffer_edits
1544                        .entry(start_region.buffer.remote_id())
1545                        .or_default()
1546                        .push(BufferEdit {
1547                            range: start_excerpt_range,
1548                            new_text: new_text.clone(),
1549                            is_insertion: true,
1550                            original_indent_column,
1551                            excerpt_id: start_region.excerpt.id,
1552                        });
1553                }
1554                let excerpt_id = end_region.excerpt.id;
1555                if end_region.buffer.capability == Capability::ReadWrite
1556                    && end_region.is_main_buffer
1557                {
1558                    edited_excerpt_ids.push(excerpt_id);
1559                    buffer_edits
1560                        .entry(end_region.buffer.remote_id())
1561                        .or_default()
1562                        .push(BufferEdit {
1563                            range: end_excerpt_range,
1564                            new_text: new_text.clone(),
1565                            is_insertion: false,
1566                            original_indent_column,
1567                            excerpt_id,
1568                        });
1569                }
1570
1571                cursor.seek(&range.start);
1572                cursor.next_excerpt();
1573                while let Some(region) = cursor.region() {
1574                    if region.excerpt.id == excerpt_id {
1575                        break;
1576                    }
1577                    if region.buffer.capability == Capability::ReadWrite && region.is_main_buffer {
1578                        edited_excerpt_ids.push(region.excerpt.id);
1579                        buffer_edits
1580                            .entry(region.buffer.remote_id())
1581                            .or_default()
1582                            .push(BufferEdit {
1583                                range: region.buffer_range.clone(),
1584                                new_text: new_text.clone(),
1585                                is_insertion: false,
1586                                original_indent_column,
1587                                excerpt_id: region.excerpt.id,
1588                            });
1589                    }
1590                    cursor.next_excerpt();
1591                }
1592            }
1593        }
1594        (buffer_edits, edited_excerpt_ids)
1595    }
1596
1597    pub fn autoindent_ranges<I, S>(&mut self, ranges: I, cx: &mut Context<Self>)
1598    where
1599        I: IntoIterator<Item = Range<S>>,
1600        S: ToOffset,
1601    {
1602        if self.read_only() || self.buffers.is_empty() {
1603            return;
1604        }
1605        self.sync_mut(cx);
1606        let empty = Arc::<str>::from("");
1607        let edits = ranges
1608            .into_iter()
1609            .map(|range| {
1610                let mut range = range.start.to_offset(self.snapshot.get_mut())
1611                    ..range.end.to_offset(&self.snapshot.get_mut());
1612                if range.start > range.end {
1613                    mem::swap(&mut range.start, &mut range.end);
1614                }
1615                (range, empty.clone())
1616            })
1617            .collect::<Vec<_>>();
1618
1619        return autoindent_ranges_internal(self, edits, cx);
1620
1621        fn autoindent_ranges_internal(
1622            this: &mut MultiBuffer,
1623            edits: Vec<(Range<MultiBufferOffset>, Arc<str>)>,
1624            cx: &mut Context<MultiBuffer>,
1625        ) {
1626            let (buffer_edits, edited_excerpt_ids) =
1627                MultiBuffer::convert_edits_to_buffer_edits(edits, this.snapshot.get_mut(), &[]);
1628
1629            let mut buffer_ids = Vec::new();
1630            for (buffer_id, mut edits) in buffer_edits {
1631                buffer_ids.push(buffer_id);
1632                edits.sort_unstable_by_key(|edit| edit.range.start);
1633
1634                let mut ranges: Vec<Range<BufferOffset>> = Vec::new();
1635                for edit in edits {
1636                    if let Some(last_range) = ranges.last_mut()
1637                        && edit.range.start <= last_range.end
1638                    {
1639                        last_range.end = last_range.end.max(edit.range.end);
1640                        continue;
1641                    }
1642                    ranges.push(edit.range);
1643                }
1644
1645                this.buffers[&buffer_id].buffer.update(cx, |buffer, cx| {
1646                    buffer.autoindent_ranges(ranges, cx);
1647                })
1648            }
1649
1650            cx.emit(Event::ExcerptsEdited {
1651                excerpt_ids: edited_excerpt_ids,
1652                buffer_ids,
1653            });
1654        }
1655    }
1656
1657    pub fn set_active_selections(
1658        &self,
1659        selections: &[Selection<Anchor>],
1660        line_mode: bool,
1661        cursor_shape: CursorShape,
1662        cx: &mut Context<Self>,
1663    ) {
1664        let mut selections_by_buffer: HashMap<BufferId, Vec<Selection<text::Anchor>>> =
1665            Default::default();
1666        let snapshot = self.read(cx);
1667        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1668        for selection in selections {
1669            let start_locator = snapshot.excerpt_locator_for_id(selection.start.excerpt_id);
1670            let end_locator = snapshot.excerpt_locator_for_id(selection.end.excerpt_id);
1671
1672            cursor.seek(&Some(start_locator), Bias::Left);
1673            while let Some(excerpt) = cursor.item()
1674                && excerpt.locator <= *end_locator
1675            {
1676                let mut start = excerpt.range.context.start;
1677                let mut end = excerpt.range.context.end;
1678                if excerpt.id == selection.start.excerpt_id {
1679                    start = selection.start.text_anchor;
1680                }
1681                if excerpt.id == selection.end.excerpt_id {
1682                    end = selection.end.text_anchor;
1683                }
1684                selections_by_buffer
1685                    .entry(excerpt.buffer_id)
1686                    .or_default()
1687                    .push(Selection {
1688                        id: selection.id,
1689                        start,
1690                        end,
1691                        reversed: selection.reversed,
1692                        goal: selection.goal,
1693                    });
1694
1695                cursor.next();
1696            }
1697        }
1698
1699        for (buffer_id, buffer_state) in self.buffers.iter() {
1700            if !selections_by_buffer.contains_key(buffer_id) {
1701                buffer_state
1702                    .buffer
1703                    .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1704            }
1705        }
1706
1707        for (buffer_id, mut selections) in selections_by_buffer {
1708            self.buffers[&buffer_id].buffer.update(cx, |buffer, cx| {
1709                selections.sort_unstable_by(|a, b| a.start.cmp(&b.start, buffer));
1710                let mut selections = selections.into_iter().peekable();
1711                let merged_selections = Arc::from_iter(iter::from_fn(|| {
1712                    let mut selection = selections.next()?;
1713                    while let Some(next_selection) = selections.peek() {
1714                        if selection.end.cmp(&next_selection.start, buffer).is_ge() {
1715                            let next_selection = selections.next().unwrap();
1716                            if next_selection.end.cmp(&selection.end, buffer).is_ge() {
1717                                selection.end = next_selection.end;
1718                            }
1719                        } else {
1720                            break;
1721                        }
1722                    }
1723                    Some(selection)
1724                }));
1725                buffer.set_active_selections(merged_selections, line_mode, cursor_shape, cx);
1726            });
1727        }
1728    }
1729
1730    pub fn remove_active_selections(&self, cx: &mut Context<Self>) {
1731        for buffer in self.buffers.values() {
1732            buffer
1733                .buffer
1734                .update(cx, |buffer, cx| buffer.remove_active_selections(cx));
1735        }
1736    }
1737
1738    #[instrument(skip_all)]
1739    fn merge_excerpt_ranges<'a>(
1740        expanded_ranges: impl IntoIterator<Item = &'a ExcerptRange<Point>> + 'a,
1741    ) -> (Vec<ExcerptRange<Point>>, Vec<usize>) {
1742        let mut merged_ranges: Vec<ExcerptRange<Point>> = Vec::new();
1743        let mut counts: Vec<usize> = Vec::new();
1744        for range in expanded_ranges {
1745            if let Some(last_range) = merged_ranges.last_mut() {
1746                assert!(
1747                    last_range.context.start <= range.context.start,
1748                    "ranges must be sorted: {last_range:?} <= {range:?}"
1749                );
1750                if last_range.context.end >= range.context.start
1751                    || last_range.context.end.row + 1 == range.context.start.row
1752                {
1753                    last_range.context.end = range.context.end.max(last_range.context.end);
1754                    *counts.last_mut().unwrap() += 1;
1755                    continue;
1756                }
1757            }
1758            merged_ranges.push(range.clone());
1759            counts.push(1);
1760        }
1761        (merged_ranges, counts)
1762    }
1763
1764    pub fn insert_excerpts_after<O>(
1765        &mut self,
1766        prev_excerpt_id: ExcerptId,
1767        buffer: Entity<Buffer>,
1768        ranges: impl IntoIterator<Item = ExcerptRange<O>>,
1769        cx: &mut Context<Self>,
1770    ) -> Vec<ExcerptId>
1771    where
1772        O: text::ToOffset,
1773    {
1774        let mut ids = Vec::new();
1775        let mut next_excerpt_id =
1776            if let Some(last_entry) = self.snapshot.borrow().excerpt_ids.last() {
1777                last_entry.id.0 + 1
1778            } else {
1779                1
1780            };
1781        self.insert_excerpts_with_ids_after(
1782            prev_excerpt_id,
1783            buffer,
1784            ranges.into_iter().map(|range| {
1785                let id = ExcerptId(post_inc(&mut next_excerpt_id));
1786                ids.push(id);
1787                (id, range)
1788            }),
1789            cx,
1790        );
1791        ids
1792    }
1793
1794    pub fn insert_excerpts_with_ids_after<O>(
1795        &mut self,
1796        prev_excerpt_id: ExcerptId,
1797        buffer: Entity<Buffer>,
1798        ranges: impl IntoIterator<Item = (ExcerptId, ExcerptRange<O>)>,
1799        cx: &mut Context<Self>,
1800    ) where
1801        O: text::ToOffset,
1802    {
1803        assert_eq!(self.history.transaction_depth(), 0);
1804        let mut ranges = ranges.into_iter().peekable();
1805        if ranges.peek().is_none() {
1806            return Default::default();
1807        }
1808
1809        self.sync_mut(cx);
1810
1811        let buffer_snapshot = buffer.read(cx).snapshot();
1812        let buffer_id = buffer_snapshot.remote_id();
1813
1814        let buffer_state = self.buffers.entry(buffer_id).or_insert_with(|| {
1815            self.buffer_changed_since_sync.replace(true);
1816            buffer.update(cx, |buffer, _| {
1817                buffer.record_changes(Rc::downgrade(&self.buffer_changed_since_sync));
1818            });
1819            BufferState {
1820                last_version: RefCell::new(buffer_snapshot.version().clone()),
1821                last_non_text_state_update_count: Cell::new(
1822                    buffer_snapshot.non_text_state_update_count(),
1823                ),
1824                excerpts: Default::default(),
1825                _subscriptions: [
1826                    cx.observe(&buffer, |_, _, cx| cx.notify()),
1827                    cx.subscribe(&buffer, Self::on_buffer_event),
1828                ],
1829                buffer: buffer.clone(),
1830            }
1831        });
1832
1833        let mut snapshot = self.snapshot.get_mut();
1834
1835        let mut prev_locator = snapshot.excerpt_locator_for_id(prev_excerpt_id).clone();
1836        let mut new_excerpt_ids = mem::take(&mut snapshot.excerpt_ids);
1837        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1838        let mut new_excerpts = cursor.slice(&prev_locator, Bias::Right);
1839        prev_locator = cursor.start().unwrap_or(Locator::min_ref()).clone();
1840
1841        let edit_start = ExcerptDimension(new_excerpts.summary().text.len);
1842        new_excerpts.update_last(
1843            |excerpt| {
1844                excerpt.has_trailing_newline = true;
1845            },
1846            (),
1847        );
1848
1849        let next_locator = if let Some(excerpt) = cursor.item() {
1850            excerpt.locator.clone()
1851        } else {
1852            Locator::max()
1853        };
1854
1855        let mut excerpts = Vec::new();
1856        let buffer_snapshot = Arc::new(buffer_snapshot);
1857        while let Some((id, range)) = ranges.next() {
1858            let locator = Locator::between(&prev_locator, &next_locator);
1859            if let Err(ix) = buffer_state.excerpts.binary_search(&locator) {
1860                buffer_state.excerpts.insert(ix, locator.clone());
1861            }
1862            let range = ExcerptRange {
1863                context: buffer_snapshot.anchor_before(&range.context.start)
1864                    ..buffer_snapshot.anchor_after(&range.context.end),
1865                primary: buffer_snapshot.anchor_before(&range.primary.start)
1866                    ..buffer_snapshot.anchor_after(&range.primary.end),
1867            };
1868            excerpts.push((id, range.clone()));
1869            let excerpt = Excerpt::new(
1870                id,
1871                locator.clone(),
1872                buffer_id,
1873                buffer_snapshot.clone(),
1874                range,
1875                ranges.peek().is_some() || cursor.item().is_some(),
1876            );
1877            new_excerpts.push(excerpt, ());
1878            prev_locator = locator.clone();
1879
1880            if let Some(last_mapping_entry) = new_excerpt_ids.last() {
1881                assert!(id > last_mapping_entry.id, "excerpt ids must be increasing");
1882            }
1883            new_excerpt_ids.push(ExcerptIdMapping { id, locator }, ());
1884        }
1885        snapshot
1886            .buffer_locators
1887            .insert(buffer_id, buffer_state.excerpts.iter().cloned().collect());
1888
1889        let edit_end = ExcerptDimension(new_excerpts.summary().text.len);
1890
1891        let suffix = cursor.suffix();
1892        let changed_trailing_excerpt = suffix.is_empty();
1893        new_excerpts.append(suffix, ());
1894        drop(cursor);
1895        snapshot.excerpts = new_excerpts;
1896        snapshot.excerpt_ids = new_excerpt_ids;
1897        if changed_trailing_excerpt {
1898            snapshot.trailing_excerpt_update_count += 1;
1899        }
1900
1901        let edits = Self::sync_diff_transforms(
1902            &mut snapshot,
1903            vec![Edit {
1904                old: edit_start..edit_start,
1905                new: edit_start..edit_end,
1906            }],
1907            DiffChangeKind::BufferEdited,
1908        );
1909        if !edits.is_empty() {
1910            self.subscriptions.publish(edits);
1911        }
1912
1913        cx.emit(Event::Edited {
1914            edited_buffer: None,
1915        });
1916        cx.emit(Event::ExcerptsAdded {
1917            buffer,
1918            predecessor: prev_excerpt_id,
1919            excerpts,
1920        });
1921        cx.notify();
1922    }
1923
1924    pub fn clear(&mut self, cx: &mut Context<Self>) {
1925        self.sync_mut(cx);
1926        let ids = self.excerpt_ids();
1927        let removed_buffer_ids = std::mem::take(&mut self.buffers).into_keys().collect();
1928        self.excerpts_by_path.clear();
1929        self.paths_by_excerpt.clear();
1930        let MultiBufferSnapshot {
1931            excerpts,
1932            buffer_locators,
1933            diffs: _,
1934            diff_transforms: _,
1935            non_text_state_update_count: _,
1936            edit_count: _,
1937            is_dirty,
1938            has_deleted_file,
1939            has_conflict,
1940            has_inverted_diff,
1941            singleton: _,
1942            excerpt_ids: _,
1943            replaced_excerpts,
1944            trailing_excerpt_update_count,
1945            all_diff_hunks_expanded: _,
1946            show_deleted_hunks: _,
1947            use_extended_diff_range: _,
1948            show_headers: _,
1949        } = self.snapshot.get_mut();
1950        buffer_locators.clear();
1951        let start = ExcerptDimension(MultiBufferOffset::ZERO);
1952        let prev_len = ExcerptDimension(excerpts.summary().text.len);
1953        *excerpts = Default::default();
1954        *trailing_excerpt_update_count += 1;
1955        *is_dirty = false;
1956        *has_deleted_file = false;
1957        *has_conflict = false;
1958        *has_inverted_diff = false;
1959        match Arc::get_mut(replaced_excerpts) {
1960            Some(replaced_excerpts) => replaced_excerpts.clear(),
1961            None => *replaced_excerpts = Default::default(),
1962        }
1963
1964        let edits = Self::sync_diff_transforms(
1965            self.snapshot.get_mut(),
1966            vec![Edit {
1967                old: start..prev_len,
1968                new: start..start,
1969            }],
1970            DiffChangeKind::BufferEdited,
1971        );
1972        if !edits.is_empty() {
1973            self.subscriptions.publish(edits);
1974        }
1975        cx.emit(Event::Edited {
1976            edited_buffer: None,
1977        });
1978        cx.emit(Event::ExcerptsRemoved {
1979            ids,
1980            removed_buffer_ids,
1981        });
1982        cx.notify();
1983    }
1984
1985    #[ztracing::instrument(skip_all)]
1986    pub fn excerpts_for_buffer(
1987        &self,
1988        buffer_id: BufferId,
1989        cx: &App,
1990    ) -> Vec<(ExcerptId, Arc<BufferSnapshot>, ExcerptRange<text::Anchor>)> {
1991        let mut excerpts = Vec::new();
1992        let snapshot = self.read(cx);
1993        let mut cursor = snapshot.excerpts.cursor::<Option<&Locator>>(());
1994        if let Some(locators) = snapshot.buffer_locators.get(&buffer_id) {
1995            for locator in &**locators {
1996                cursor.seek_forward(&Some(locator), Bias::Left);
1997                if let Some(excerpt) = cursor.item()
1998                    && excerpt.locator == *locator
1999                {
2000                    excerpts.push((excerpt.id, excerpt.buffer.clone(), excerpt.range.clone()));
2001                }
2002            }
2003        }
2004
2005        excerpts
2006    }
2007
2008    pub fn excerpt_ranges_for_buffer(&self, buffer_id: BufferId, cx: &App) -> Vec<Range<Point>> {
2009        let snapshot = self.read(cx);
2010        let mut excerpts = snapshot
2011            .excerpts
2012            .cursor::<Dimensions<Option<&Locator>, ExcerptPoint>>(());
2013        let mut diff_transforms = snapshot
2014            .diff_transforms
2015            .cursor::<Dimensions<ExcerptPoint, OutputDimension<Point>>>(());
2016        diff_transforms.next();
2017        let locators = snapshot
2018            .buffer_locators
2019            .get(&buffer_id)
2020            .into_iter()
2021            .flat_map(|v| &**v);
2022        let mut result = Vec::new();
2023        for locator in locators {
2024            excerpts.seek_forward(&Some(locator), Bias::Left);
2025            if let Some(excerpt) = excerpts.item()
2026                && excerpt.locator == *locator
2027            {
2028                let excerpt_start = excerpts.start().1;
2029                let excerpt_end = excerpt_start + excerpt.text_summary.lines;
2030
2031                diff_transforms.seek_forward(&excerpt_start, Bias::Left);
2032                let overshoot = excerpt_start - diff_transforms.start().0;
2033                let start = diff_transforms.start().1 + overshoot;
2034
2035                diff_transforms.seek_forward(&excerpt_end, Bias::Right);
2036                let overshoot = excerpt_end - diff_transforms.start().0;
2037                let end = diff_transforms.start().1 + overshoot;
2038
2039                result.push(start.0..end.0)
2040            }
2041        }
2042        result
2043    }
2044
2045    pub fn excerpt_buffer_ids(&self) -> Vec<BufferId> {
2046        self.snapshot
2047            .borrow()
2048            .excerpts
2049            .iter()
2050            .map(|entry| entry.buffer_id)
2051            .collect()
2052    }
2053
2054    pub fn excerpt_ids(&self) -> Vec<ExcerptId> {
2055        let snapshot = self.snapshot.borrow();
2056        let mut ids = Vec::with_capacity(snapshot.excerpts.summary().count);
2057        ids.extend(snapshot.excerpts.iter().map(|entry| entry.id));
2058        ids
2059    }
2060
2061    pub fn excerpt_containing(
2062        &self,
2063        position: impl ToOffset,
2064        cx: &App,
2065    ) -> Option<(ExcerptId, Entity<Buffer>, Range<text::Anchor>)> {
2066        let snapshot = self.read(cx);
2067        let offset = position.to_offset(&snapshot);
2068
2069        let mut cursor = snapshot.cursor::<MultiBufferOffset, BufferOffset>();
2070        cursor.seek(&offset);
2071        cursor
2072            .excerpt()
2073            .or_else(|| snapshot.excerpts.last())
2074            .map(|excerpt| {
2075                (
2076                    excerpt.id,
2077                    self.buffers.get(&excerpt.buffer_id).unwrap().buffer.clone(),
2078                    excerpt.range.context.clone(),
2079                )
2080            })
2081    }
2082
2083    pub fn buffer_for_anchor(&self, anchor: Anchor, cx: &App) -> Option<Entity<Buffer>> {
2084        if let Some(buffer_id) = anchor.text_anchor.buffer_id {
2085            self.buffer(buffer_id)
2086        } else {
2087            let (_, buffer, _) = self.excerpt_containing(anchor, cx)?;
2088            Some(buffer)
2089        }
2090    }
2091
2092    // If point is at the end of the buffer, the last excerpt is returned
2093    pub fn point_to_buffer_offset<T: ToOffset>(
2094        &self,
2095        point: T,
2096        cx: &App,
2097    ) -> Option<(Entity<Buffer>, BufferOffset)> {
2098        let snapshot = self.read(cx);
2099        let (buffer, offset) = snapshot.point_to_buffer_offset(point)?;
2100        Some((
2101            self.buffers.get(&buffer.remote_id())?.buffer.clone(),
2102            offset,
2103        ))
2104    }
2105
2106    // If point is at the end of the buffer, the last excerpt is returned
2107    pub fn point_to_buffer_point<T: ToPoint>(
2108        &self,
2109        point: T,
2110        cx: &App,
2111    ) -> Option<(Entity<Buffer>, Point, ExcerptId)> {
2112        let snapshot = self.read(cx);
2113        let (buffer, point, is_main_buffer) =
2114            snapshot.point_to_buffer_point(point.to_point(&snapshot))?;
2115        Some((
2116            self.buffers.get(&buffer.remote_id())?.buffer.clone(),
2117            point,
2118            is_main_buffer,
2119        ))
2120    }
2121
2122    pub fn buffer_point_to_anchor(
2123        &self,
2124        // todo(lw): We shouldn't need this?
2125        buffer: &Entity<Buffer>,
2126        point: Point,
2127        cx: &App,
2128    ) -> Option<Anchor> {
2129        let mut found = None;
2130        let snapshot = buffer.read(cx).snapshot();
2131        for (excerpt_id, _, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2132            let start = range.context.start.to_point(&snapshot);
2133            let end = range.context.end.to_point(&snapshot);
2134            if start <= point && point < end {
2135                found = Some((snapshot.clip_point(point, Bias::Left), excerpt_id));
2136                break;
2137            }
2138            if point < start {
2139                found = Some((start, excerpt_id));
2140            }
2141            if point > end {
2142                found = Some((end, excerpt_id));
2143            }
2144        }
2145
2146        found.map(|(point, excerpt_id)| {
2147            let text_anchor = snapshot.anchor_after(point);
2148            Anchor::in_buffer(excerpt_id, text_anchor)
2149        })
2150    }
2151
2152    pub fn buffer_anchor_to_anchor(
2153        &self,
2154        // todo(lw): We shouldn't need this?
2155        buffer: &Entity<Buffer>,
2156        anchor: text::Anchor,
2157        cx: &App,
2158    ) -> Option<Anchor> {
2159        let snapshot = buffer.read(cx).snapshot();
2160        for (excerpt_id, _, range) in self.excerpts_for_buffer(snapshot.remote_id(), cx) {
2161            if range.context.start.cmp(&anchor, &snapshot).is_le()
2162                && range.context.end.cmp(&anchor, &snapshot).is_ge()
2163            {
2164                return Some(Anchor::in_buffer(excerpt_id, anchor));
2165            }
2166        }
2167
2168        None
2169    }
2170
2171    pub fn merge_excerpts(
2172        &mut self,
2173        excerpt_ids: &[ExcerptId],
2174        cx: &mut Context<Self>,
2175    ) -> ExcerptId {
2176        debug_assert!(!excerpt_ids.is_empty());
2177        if excerpt_ids.len() == 1 {
2178            return excerpt_ids[0];
2179        }
2180
2181        let snapshot = self.snapshot(cx);
2182
2183        let first_range = snapshot
2184            .context_range_for_excerpt(excerpt_ids[0])
2185            .expect("first excerpt must exist");
2186        let last_range = snapshot
2187            .context_range_for_excerpt(*excerpt_ids.last().unwrap())
2188            .expect("last excerpt must exist");
2189
2190        let union_range = first_range.start..last_range.end;
2191
2192        drop(snapshot);
2193
2194        self.resize_excerpt(excerpt_ids[0], union_range, cx);
2195        let removed = &excerpt_ids[1..];
2196        for &excerpt_id in removed {
2197            if let Some(path) = self.paths_by_excerpt.get(&excerpt_id) {
2198                if let Some(excerpt_list) = self.excerpts_by_path.get_mut(path) {
2199                    excerpt_list.retain(|id| *id != excerpt_id);
2200                    if excerpt_list.is_empty() {
2201                        let path = path.clone();
2202                        self.excerpts_by_path.remove(&path);
2203                    }
2204                }
2205            }
2206        }
2207        self.remove_excerpts(removed.iter().copied(), cx);
2208
2209        excerpt_ids[0]
2210    }
2211
2212    pub fn remove_excerpts(
2213        &mut self,
2214        excerpt_ids: impl IntoIterator<Item = ExcerptId>,
2215        cx: &mut Context<Self>,
2216    ) {
2217        self.sync_mut(cx);
2218        let ids = excerpt_ids.into_iter().collect::<Vec<_>>();
2219        if ids.is_empty() {
2220            return;
2221        }
2222        self.buffer_changed_since_sync.replace(true);
2223
2224        let mut snapshot = self.snapshot.get_mut();
2225        let mut new_excerpts = SumTree::default();
2226        let mut cursor = snapshot
2227            .excerpts
2228            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2229        let mut edits = Vec::new();
2230        let mut excerpt_ids = ids.iter().copied().peekable();
2231        let mut removed_buffer_ids = Vec::new();
2232        let mut removed_excerpts_for_buffers = HashSet::default();
2233
2234        while let Some(excerpt_id) = excerpt_ids.next() {
2235            self.paths_by_excerpt.remove(&excerpt_id);
2236            // Seek to the next excerpt to remove, preserving any preceding excerpts.
2237            let locator = snapshot.excerpt_locator_for_id(excerpt_id);
2238            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
2239
2240            if let Some(mut excerpt) = cursor.item() {
2241                if excerpt.id != excerpt_id {
2242                    continue;
2243                }
2244                let mut old_start = cursor.start().1;
2245
2246                // Skip over the removed excerpt.
2247                'remove_excerpts: loop {
2248                    if let Some(buffer_state) = self.buffers.get_mut(&excerpt.buffer_id) {
2249                        removed_excerpts_for_buffers.insert(excerpt.buffer_id);
2250                        buffer_state.excerpts.retain(|l| l != &excerpt.locator);
2251                        if buffer_state.excerpts.is_empty() {
2252                            log::debug!(
2253                                "removing buffer and diff for buffer {}",
2254                                excerpt.buffer_id
2255                            );
2256                            self.buffers.remove(&excerpt.buffer_id);
2257                            removed_buffer_ids.push(excerpt.buffer_id);
2258                        }
2259                    }
2260                    cursor.next();
2261
2262                    // Skip over any subsequent excerpts that are also removed.
2263                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
2264                        let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
2265                        if let Some(next_excerpt) = cursor.item()
2266                            && next_excerpt.locator == *next_locator
2267                        {
2268                            excerpt_ids.next();
2269                            excerpt = next_excerpt;
2270                            continue 'remove_excerpts;
2271                        }
2272                    }
2273
2274                    break;
2275                }
2276
2277                // When removing the last excerpt, remove the trailing newline from
2278                // the previous excerpt.
2279                if cursor.item().is_none() && old_start > MultiBufferOffset::ZERO {
2280                    old_start -= 1;
2281                    new_excerpts.update_last(|e| e.has_trailing_newline = false, ());
2282                }
2283
2284                // Push an edit for the removal of this run of excerpts.
2285                let old_end = cursor.start().1;
2286                let new_start = ExcerptDimension(new_excerpts.summary().text.len);
2287                edits.push(Edit {
2288                    old: old_start..old_end,
2289                    new: new_start..new_start,
2290                });
2291            }
2292        }
2293        let suffix = cursor.suffix();
2294        let changed_trailing_excerpt = suffix.is_empty();
2295        new_excerpts.append(suffix, ());
2296        drop(cursor);
2297        for buffer_id in removed_excerpts_for_buffers {
2298            match self.buffers.get(&buffer_id) {
2299                Some(buffer_state) => {
2300                    snapshot
2301                        .buffer_locators
2302                        .insert(buffer_id, buffer_state.excerpts.iter().cloned().collect());
2303                }
2304                None => {
2305                    snapshot.buffer_locators.remove(&buffer_id);
2306                }
2307            }
2308        }
2309        snapshot.excerpts = new_excerpts;
2310        for buffer_id in &removed_buffer_ids {
2311            self.diffs.remove(buffer_id);
2312            snapshot.diffs.remove(buffer_id);
2313        }
2314
2315        // Recalculate has_inverted_diff after removing diffs
2316        if !removed_buffer_ids.is_empty() {
2317            snapshot.has_inverted_diff = snapshot
2318                .diffs
2319                .iter()
2320                .any(|(_, diff)| diff.main_buffer.is_some());
2321        }
2322
2323        if changed_trailing_excerpt {
2324            snapshot.trailing_excerpt_update_count += 1;
2325        }
2326
2327        let edits = Self::sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2328        if !edits.is_empty() {
2329            self.subscriptions.publish(edits);
2330        }
2331        cx.emit(Event::Edited {
2332            edited_buffer: None,
2333        });
2334        cx.emit(Event::ExcerptsRemoved {
2335            ids,
2336            removed_buffer_ids,
2337        });
2338        cx.notify();
2339    }
2340
2341    pub fn wait_for_anchors<'a, Anchors: 'a + Iterator<Item = Anchor>>(
2342        &self,
2343        anchors: Anchors,
2344        cx: &mut Context<Self>,
2345    ) -> impl 'static + Future<Output = Result<()>> + use<Anchors> {
2346        let mut error = None;
2347        let mut futures = Vec::new();
2348        for anchor in anchors {
2349            if let Some(buffer_id) = anchor.text_anchor.buffer_id {
2350                if let Some(buffer) = self.buffers.get(&buffer_id) {
2351                    buffer.buffer.update(cx, |buffer, _| {
2352                        futures.push(buffer.wait_for_anchors([anchor.text_anchor]))
2353                    });
2354                } else {
2355                    error = Some(anyhow!(
2356                        "buffer {buffer_id} is not part of this multi-buffer"
2357                    ));
2358                    break;
2359                }
2360            }
2361        }
2362        async move {
2363            if let Some(error) = error {
2364                Err(error)?;
2365            }
2366            for future in futures {
2367                future.await?;
2368            }
2369            Ok(())
2370        }
2371    }
2372
2373    pub fn text_anchor_for_position<T: ToOffset>(
2374        &self,
2375        position: T,
2376        cx: &App,
2377    ) -> Option<(Entity<Buffer>, language::Anchor)> {
2378        let snapshot = self.read(cx);
2379        let anchor = snapshot.anchor_before(position);
2380        let buffer = self
2381            .buffers
2382            .get(&anchor.text_anchor.buffer_id?)?
2383            .buffer
2384            .clone();
2385        Some((buffer, anchor.text_anchor))
2386    }
2387
2388    fn on_buffer_event(
2389        &mut self,
2390        buffer: Entity<Buffer>,
2391        event: &language::BufferEvent,
2392        cx: &mut Context<Self>,
2393    ) {
2394        use language::BufferEvent;
2395        let buffer_id = buffer.read(cx).remote_id();
2396        cx.emit(match event {
2397            BufferEvent::Edited => Event::Edited {
2398                edited_buffer: Some(buffer),
2399            },
2400            BufferEvent::DirtyChanged => Event::DirtyChanged,
2401            BufferEvent::Saved => Event::Saved,
2402            BufferEvent::FileHandleChanged => Event::FileHandleChanged,
2403            BufferEvent::Reloaded => Event::Reloaded,
2404            BufferEvent::LanguageChanged(has_language) => {
2405                Event::LanguageChanged(buffer_id, *has_language)
2406            }
2407            BufferEvent::Reparsed => Event::Reparsed(buffer_id),
2408            BufferEvent::DiagnosticsUpdated => Event::DiagnosticsUpdated,
2409            BufferEvent::CapabilityChanged => {
2410                self.capability = buffer.read(cx).capability();
2411                return;
2412            }
2413            BufferEvent::Operation { .. } | BufferEvent::ReloadNeeded => return,
2414        });
2415    }
2416
2417    fn buffer_diff_language_changed(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2418        let diff = diff.read(cx);
2419        let buffer_id = diff.buffer_id;
2420        let diff = DiffStateSnapshot {
2421            diff: diff.snapshot(cx),
2422            main_buffer: None,
2423        };
2424        self.snapshot.get_mut().diffs.insert(buffer_id, diff);
2425    }
2426
2427    fn inverted_buffer_diff_language_changed(
2428        &mut self,
2429        diff: Entity<BufferDiff>,
2430        main_buffer: Entity<language::Buffer>,
2431        cx: &mut Context<Self>,
2432    ) {
2433        let base_text_buffer_id = diff.read(cx).base_text_buffer().read(cx).remote_id();
2434        let main_buffer_snapshot = main_buffer.read(cx).snapshot();
2435        let diff = diff.read(cx);
2436        let diff = DiffStateSnapshot {
2437            diff: diff.snapshot(cx),
2438            main_buffer: Some(main_buffer_snapshot),
2439        };
2440        self.snapshot
2441            .get_mut()
2442            .diffs
2443            .insert(base_text_buffer_id, diff);
2444    }
2445
2446    fn buffer_diff_changed(
2447        &mut self,
2448        diff: Entity<BufferDiff>,
2449        range: Range<text::Anchor>,
2450        cx: &mut Context<Self>,
2451    ) {
2452        self.sync_mut(cx);
2453
2454        let diff = diff.read(cx);
2455        let buffer_id = diff.buffer_id;
2456
2457        let new_diff = DiffStateSnapshot {
2458            diff: diff.snapshot(cx),
2459            main_buffer: None,
2460        };
2461        let mut snapshot = self.snapshot.get_mut();
2462        let base_text_changed = snapshot
2463            .diffs
2464            .get(&buffer_id)
2465            .is_none_or(|old_diff| !new_diff.base_texts_definitely_eq(old_diff));
2466        snapshot.diffs.insert_or_replace(buffer_id, new_diff);
2467
2468        let Some(buffer_state) = self.buffers.get(&buffer_id) else {
2469            return;
2470        };
2471
2472        let buffer = buffer_state.buffer.read(cx);
2473        let diff_change_range = range.to_offset(buffer);
2474
2475        let excerpt_edits = snapshot.excerpt_edits_for_diff_change(buffer_state, diff_change_range);
2476        let edits = Self::sync_diff_transforms(
2477            &mut snapshot,
2478            excerpt_edits,
2479            DiffChangeKind::DiffUpdated {
2480                base_changed: base_text_changed,
2481            },
2482        );
2483        if !edits.is_empty() {
2484            self.subscriptions.publish(edits);
2485        }
2486        cx.emit(Event::Edited {
2487            edited_buffer: None,
2488        });
2489    }
2490
2491    fn inverted_buffer_diff_changed(
2492        &mut self,
2493        diff: Entity<BufferDiff>,
2494        main_buffer: Entity<language::Buffer>,
2495        diff_change_range: Option<Range<usize>>,
2496        cx: &mut Context<Self>,
2497    ) {
2498        self.sync_mut(cx);
2499
2500        let base_text_buffer_id = diff.read(cx).base_text_buffer().read(cx).remote_id();
2501        let Some(buffer_state) = self.buffers.get(&base_text_buffer_id) else {
2502            return;
2503        };
2504
2505        let main_buffer_snapshot = main_buffer.read(cx).snapshot();
2506        let diff = diff.read(cx);
2507        let new_diff = DiffStateSnapshot {
2508            diff: diff.snapshot(cx),
2509            main_buffer: Some(main_buffer_snapshot),
2510        };
2511        let mut snapshot = self.snapshot.get_mut();
2512        snapshot
2513            .diffs
2514            .insert_or_replace(base_text_buffer_id, new_diff);
2515
2516        let Some(diff_change_range) = diff_change_range else {
2517            return;
2518        };
2519
2520        let excerpt_edits = snapshot.excerpt_edits_for_diff_change(buffer_state, diff_change_range);
2521        let edits = Self::sync_diff_transforms(
2522            &mut snapshot,
2523            excerpt_edits,
2524            DiffChangeKind::DiffUpdated {
2525                // We don't read this field for inverted diffs.
2526                base_changed: false,
2527            },
2528        );
2529        if !edits.is_empty() {
2530            self.subscriptions.publish(edits);
2531        }
2532        cx.emit(Event::Edited {
2533            edited_buffer: None,
2534        });
2535    }
2536
2537    pub fn all_buffers_iter(&self) -> impl Iterator<Item = Entity<Buffer>> {
2538        self.buffers.values().map(|state| state.buffer.clone())
2539    }
2540
2541    pub fn all_buffers(&self) -> HashSet<Entity<Buffer>> {
2542        self.all_buffers_iter().collect()
2543    }
2544
2545    pub fn all_buffer_ids_iter(&self) -> impl Iterator<Item = BufferId> {
2546        self.buffers.keys().copied()
2547    }
2548
2549    pub fn all_buffer_ids(&self) -> Vec<BufferId> {
2550        self.all_buffer_ids_iter().collect()
2551    }
2552
2553    pub fn buffer(&self, buffer_id: BufferId) -> Option<Entity<Buffer>> {
2554        self.buffers
2555            .get(&buffer_id)
2556            .map(|state| state.buffer.clone())
2557    }
2558
2559    pub fn language_at<T: ToOffset>(&self, point: T, cx: &App) -> Option<Arc<Language>> {
2560        self.point_to_buffer_offset(point, cx)
2561            .and_then(|(buffer, offset)| buffer.read(cx).language_at(offset))
2562    }
2563
2564    pub fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
2565        let buffer_id = self
2566            .snapshot
2567            .borrow()
2568            .excerpts
2569            .first()
2570            .map(|excerpt| excerpt.buffer.remote_id());
2571        buffer_id
2572            .and_then(|buffer_id| self.buffer(buffer_id))
2573            .map(|buffer| {
2574                let buffer = buffer.read(cx);
2575                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx)
2576            })
2577            .unwrap_or_else(move || self.language_settings_at(MultiBufferOffset::default(), cx))
2578    }
2579
2580    pub fn language_settings_at<'a, T: ToOffset>(
2581        &'a self,
2582        point: T,
2583        cx: &'a App,
2584    ) -> Cow<'a, LanguageSettings> {
2585        let mut language = None;
2586        let mut file = None;
2587        if let Some((buffer, offset)) = self.point_to_buffer_offset(point, cx) {
2588            let buffer = buffer.read(cx);
2589            language = buffer.language_at(offset);
2590            file = buffer.file();
2591        }
2592        language_settings(language.map(|l| l.name()), file, cx)
2593    }
2594
2595    pub fn for_each_buffer(&self, f: &mut dyn FnMut(&Entity<Buffer>)) {
2596        self.buffers.values().for_each(|state| f(&state.buffer))
2597    }
2598
2599    pub fn explicit_title(&self) -> Option<&str> {
2600        self.title.as_deref()
2601    }
2602
2603    pub fn title<'a>(&'a self, cx: &'a App) -> Cow<'a, str> {
2604        if let Some(title) = self.title.as_ref() {
2605            return title.into();
2606        }
2607
2608        if let Some(buffer) = self.as_singleton() {
2609            let buffer = buffer.read(cx);
2610
2611            if let Some(file) = buffer.file() {
2612                return file.file_name(cx).into();
2613            }
2614
2615            if let Some(title) = self.buffer_content_title(buffer) {
2616                return title;
2617            }
2618        };
2619
2620        "untitled".into()
2621    }
2622
2623    fn buffer_content_title(&self, buffer: &Buffer) -> Option<Cow<'_, str>> {
2624        let mut is_leading_whitespace = true;
2625        let mut count = 0;
2626        let mut prev_was_space = false;
2627        let mut title = String::new();
2628
2629        for ch in buffer.snapshot().chars() {
2630            if is_leading_whitespace && ch.is_whitespace() {
2631                continue;
2632            }
2633
2634            is_leading_whitespace = false;
2635
2636            if ch == '\n' || count >= 40 {
2637                break;
2638            }
2639
2640            if ch.is_whitespace() {
2641                if !prev_was_space {
2642                    title.push(' ');
2643                    count += 1;
2644                    prev_was_space = true;
2645                }
2646            } else {
2647                title.push(ch);
2648                count += 1;
2649                prev_was_space = false;
2650            }
2651        }
2652
2653        let title = title.trim_end().to_string();
2654
2655        if title.is_empty() {
2656            return None;
2657        }
2658
2659        Some(title.into())
2660    }
2661
2662    pub fn set_title(&mut self, title: String, cx: &mut Context<Self>) {
2663        self.title = Some(title);
2664        cx.notify();
2665    }
2666
2667    /// Preserve preview tabs containing this multibuffer until additional edits occur.
2668    pub fn refresh_preview(&self, cx: &mut Context<Self>) {
2669        for buffer_state in self.buffers.values() {
2670            buffer_state
2671                .buffer
2672                .update(cx, |buffer, _cx| buffer.refresh_preview());
2673        }
2674    }
2675
2676    /// Whether we should preserve the preview status of a tab containing this multi-buffer.
2677    pub fn preserve_preview(&self, cx: &App) -> bool {
2678        self.buffers
2679            .values()
2680            .all(|state| state.buffer.read(cx).preserve_preview())
2681    }
2682
2683    #[cfg(any(test, feature = "test-support"))]
2684    pub fn is_parsing(&self, cx: &App) -> bool {
2685        self.as_singleton().unwrap().read(cx).is_parsing()
2686    }
2687
2688    pub fn add_diff(&mut self, diff: Entity<BufferDiff>, cx: &mut Context<Self>) {
2689        let buffer_id = diff.read(cx).buffer_id;
2690
2691        if let Some(existing_diff) = self.diff_for(buffer_id)
2692            && diff.entity_id() == existing_diff.entity_id()
2693        {
2694            return;
2695        }
2696
2697        self.buffer_diff_changed(
2698            diff.clone(),
2699            text::Anchor::min_max_range_for_buffer(buffer_id),
2700            cx,
2701        );
2702        self.diffs.insert(buffer_id, DiffState::new(diff, cx));
2703    }
2704
2705    pub fn add_inverted_diff(
2706        &mut self,
2707        diff: Entity<BufferDiff>,
2708        main_buffer: Entity<language::Buffer>,
2709        cx: &mut Context<Self>,
2710    ) {
2711        let snapshot = diff.read(cx).base_text(cx);
2712        let base_text_buffer_id = snapshot.remote_id();
2713        let diff_change_range = 0..snapshot.len();
2714        self.snapshot.get_mut().has_inverted_diff = true;
2715        self.inverted_buffer_diff_changed(
2716            diff.clone(),
2717            main_buffer.clone(),
2718            Some(diff_change_range),
2719            cx,
2720        );
2721        self.diffs.insert(
2722            base_text_buffer_id,
2723            DiffState::new_inverted(diff, main_buffer, cx),
2724        );
2725    }
2726
2727    pub fn diff_for(&self, buffer_id: BufferId) -> Option<Entity<BufferDiff>> {
2728        self.diffs.get(&buffer_id).map(|state| state.diff.clone())
2729    }
2730
2731    pub fn expand_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2732        self.expand_or_collapse_diff_hunks(ranges, true, cx);
2733    }
2734
2735    pub fn collapse_diff_hunks(&mut self, ranges: Vec<Range<Anchor>>, cx: &mut Context<Self>) {
2736        self.expand_or_collapse_diff_hunks(ranges, false, cx);
2737    }
2738
2739    pub fn set_all_diff_hunks_expanded(&mut self, cx: &mut Context<Self>) {
2740        self.snapshot.get_mut().all_diff_hunks_expanded = true;
2741        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], true, cx);
2742    }
2743
2744    pub fn all_diff_hunks_expanded(&self) -> bool {
2745        self.snapshot.borrow().all_diff_hunks_expanded
2746    }
2747
2748    pub fn set_all_diff_hunks_collapsed(&mut self, cx: &mut Context<Self>) {
2749        self.snapshot.get_mut().all_diff_hunks_expanded = false;
2750        self.expand_or_collapse_diff_hunks(vec![Anchor::min()..Anchor::max()], false, cx);
2751    }
2752
2753    pub fn set_show_deleted_hunks(&mut self, show: bool, cx: &mut Context<Self>) {
2754        self.snapshot.get_mut().show_deleted_hunks = show;
2755
2756        self.sync_mut(cx);
2757
2758        let old_len = self.snapshot.borrow().len();
2759
2760        let ranges = std::iter::once((Point::zero()..Point::MAX, ExcerptId::max()));
2761        let _ = self.expand_or_collapse_diff_hunks_inner(ranges, true, cx);
2762
2763        let new_len = self.snapshot.borrow().len();
2764
2765        self.subscriptions.publish(vec![Edit {
2766            old: MultiBufferOffset(0)..old_len,
2767            new: MultiBufferOffset(0)..new_len,
2768        }]);
2769
2770        cx.emit(Event::DiffHunksToggled);
2771        cx.emit(Event::Edited {
2772            edited_buffer: None,
2773        });
2774    }
2775
2776    pub fn set_use_extended_diff_range(&mut self, use_extended: bool, _cx: &mut Context<Self>) {
2777        self.snapshot.get_mut().use_extended_diff_range = use_extended;
2778    }
2779
2780    pub fn has_multiple_hunks(&self, cx: &App) -> bool {
2781        self.read(cx)
2782            .diff_hunks_in_range(Anchor::min()..Anchor::max())
2783            .nth(1)
2784            .is_some()
2785    }
2786
2787    pub fn single_hunk_is_expanded(&self, range: Range<Anchor>, cx: &App) -> bool {
2788        let snapshot = self.read(cx);
2789        let mut cursor = snapshot.diff_transforms.cursor::<MultiBufferOffset>(());
2790        let offset_range = range.to_offset(&snapshot);
2791        cursor.seek(&offset_range.start, Bias::Left);
2792        while let Some(item) = cursor.item() {
2793            if *cursor.start() >= offset_range.end && *cursor.start() > offset_range.start {
2794                break;
2795            }
2796            if item.hunk_info().is_some() {
2797                return true;
2798            }
2799            cursor.next();
2800        }
2801        false
2802    }
2803
2804    pub fn has_expanded_diff_hunks_in_ranges(&self, ranges: &[Range<Anchor>], cx: &App) -> bool {
2805        let snapshot = self.read(cx);
2806        let mut cursor = snapshot.diff_transforms.cursor::<MultiBufferOffset>(());
2807        for range in ranges {
2808            let range = range.to_point(&snapshot);
2809            let start = snapshot.point_to_offset(Point::new(range.start.row, 0));
2810            let end = (snapshot.point_to_offset(Point::new(range.end.row + 1, 0)) + 1usize)
2811                .min(snapshot.len());
2812            cursor.seek(&start, Bias::Right);
2813            while let Some(item) = cursor.item() {
2814                if *cursor.start() >= end {
2815                    break;
2816                }
2817                if item.hunk_info().is_some() {
2818                    return true;
2819                }
2820                cursor.next();
2821            }
2822        }
2823        false
2824    }
2825
2826    pub fn expand_or_collapse_diff_hunks_inner(
2827        &mut self,
2828        ranges: impl IntoIterator<Item = (Range<Point>, ExcerptId)>,
2829        expand: bool,
2830        cx: &mut Context<Self>,
2831    ) -> Vec<Edit<MultiBufferOffset>> {
2832        if self.snapshot.borrow().all_diff_hunks_expanded && !expand {
2833            return Vec::new();
2834        }
2835        self.sync_mut(cx);
2836        let mut snapshot = self.snapshot.get_mut();
2837        let mut excerpt_edits = Vec::new();
2838        let mut last_hunk_row = None;
2839        for (range, end_excerpt_id) in ranges {
2840            for diff_hunk in snapshot.diff_hunks_in_range(range) {
2841                if diff_hunk.excerpt_id.cmp(&end_excerpt_id, &snapshot).is_gt() {
2842                    continue;
2843                }
2844                if last_hunk_row.is_some_and(|row| row >= diff_hunk.row_range.start) {
2845                    continue;
2846                }
2847                let start = Anchor::in_buffer(diff_hunk.excerpt_id, diff_hunk.buffer_range.start);
2848                let end = Anchor::in_buffer(diff_hunk.excerpt_id, diff_hunk.buffer_range.end);
2849                let start = snapshot.excerpt_offset_for_anchor(&start);
2850                let end = snapshot.excerpt_offset_for_anchor(&end);
2851                last_hunk_row = Some(diff_hunk.row_range.start);
2852                excerpt_edits.push(text::Edit {
2853                    old: start..end,
2854                    new: start..end,
2855                });
2856            }
2857        }
2858
2859        Self::sync_diff_transforms(
2860            &mut snapshot,
2861            excerpt_edits,
2862            DiffChangeKind::ExpandOrCollapseHunks { expand },
2863        )
2864    }
2865
2866    pub fn expand_or_collapse_diff_hunks(
2867        &mut self,
2868        ranges: Vec<Range<Anchor>>,
2869        expand: bool,
2870        cx: &mut Context<Self>,
2871    ) {
2872        let snapshot = self.snapshot.borrow().clone();
2873        let ranges = ranges.iter().map(move |range| {
2874            let end_excerpt_id = range.end.excerpt_id;
2875            let range = range.to_point(&snapshot);
2876            let mut peek_end = range.end;
2877            if range.end.row < snapshot.max_row().0 {
2878                peek_end = Point::new(range.end.row + 1, 0);
2879            };
2880            (range.start..peek_end, end_excerpt_id)
2881        });
2882        let edits = self.expand_or_collapse_diff_hunks_inner(ranges, expand, cx);
2883        if !edits.is_empty() {
2884            self.subscriptions.publish(edits);
2885        }
2886        cx.emit(Event::DiffHunksToggled);
2887        cx.emit(Event::Edited {
2888            edited_buffer: None,
2889        });
2890    }
2891
2892    pub fn resize_excerpt(
2893        &mut self,
2894        id: ExcerptId,
2895        range: Range<text::Anchor>,
2896        cx: &mut Context<Self>,
2897    ) {
2898        self.sync_mut(cx);
2899
2900        let mut snapshot = self.snapshot.get_mut();
2901        let locator = snapshot.excerpt_locator_for_id(id);
2902        let mut new_excerpts = SumTree::default();
2903        let mut cursor = snapshot
2904            .excerpts
2905            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2906        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2907
2908        let prefix = cursor.slice(&Some(locator), Bias::Left);
2909        new_excerpts.append(prefix, ());
2910
2911        let mut excerpt = cursor.item().unwrap().clone();
2912        let old_text_len = excerpt.text_summary.len;
2913
2914        excerpt.range.context.start = range.start;
2915        excerpt.range.context.end = range.end;
2916        excerpt.max_buffer_row = range.end.to_point(&excerpt.buffer).row;
2917
2918        excerpt.text_summary = excerpt
2919            .buffer
2920            .text_summary_for_range(excerpt.range.context.clone());
2921
2922        let new_start_offset = ExcerptDimension(new_excerpts.summary().text.len);
2923        let old_start_offset = cursor.start().1;
2924        let new_text_len = excerpt.text_summary.len;
2925        let edit = Edit {
2926            old: old_start_offset..old_start_offset + old_text_len,
2927            new: new_start_offset..new_start_offset + new_text_len,
2928        };
2929
2930        if let Some(last_edit) = edits.last_mut() {
2931            if last_edit.old.end == edit.old.start {
2932                last_edit.old.end = edit.old.end;
2933                last_edit.new.end = edit.new.end;
2934            } else {
2935                edits.push(edit);
2936            }
2937        } else {
2938            edits.push(edit);
2939        }
2940
2941        new_excerpts.push(excerpt, ());
2942
2943        cursor.next();
2944
2945        new_excerpts.append(cursor.suffix(), ());
2946
2947        drop(cursor);
2948        snapshot.excerpts = new_excerpts;
2949
2950        let edits = Self::sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
2951        if !edits.is_empty() {
2952            self.subscriptions.publish(edits);
2953        }
2954        cx.emit(Event::Edited {
2955            edited_buffer: None,
2956        });
2957        cx.emit(Event::ExcerptsExpanded { ids: vec![id] });
2958        cx.notify();
2959    }
2960
2961    pub fn expand_excerpts(
2962        &mut self,
2963        ids: impl IntoIterator<Item = ExcerptId>,
2964        line_count: u32,
2965        direction: ExpandExcerptDirection,
2966        cx: &mut Context<Self>,
2967    ) {
2968        if line_count == 0 {
2969            return;
2970        }
2971        self.sync_mut(cx);
2972        if !self.excerpts_by_path.is_empty() {
2973            self.expand_excerpts_with_paths(ids, line_count, direction, cx);
2974            return;
2975        }
2976        let mut snapshot = self.snapshot.get_mut();
2977
2978        let ids = ids.into_iter().collect::<Vec<_>>();
2979        let locators = snapshot.excerpt_locators_for_ids(ids.iter().copied());
2980        let mut new_excerpts = SumTree::default();
2981        let mut cursor = snapshot
2982            .excerpts
2983            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
2984        let mut edits = Vec::<Edit<ExcerptOffset>>::new();
2985
2986        for locator in &locators {
2987            let prefix = cursor.slice(&Some(locator), Bias::Left);
2988            new_excerpts.append(prefix, ());
2989
2990            let mut excerpt = cursor.item().unwrap().clone();
2991            let old_text_len = excerpt.text_summary.len;
2992
2993            let up_line_count = if direction.should_expand_up() {
2994                line_count
2995            } else {
2996                0
2997            };
2998
2999            let start_row = excerpt
3000                .range
3001                .context
3002                .start
3003                .to_point(&excerpt.buffer)
3004                .row
3005                .saturating_sub(up_line_count);
3006            let start_point = Point::new(start_row, 0);
3007            excerpt.range.context.start = excerpt.buffer.anchor_before(start_point);
3008
3009            let down_line_count = if direction.should_expand_down() {
3010                line_count
3011            } else {
3012                0
3013            };
3014
3015            let mut end_point = excerpt.buffer.clip_point(
3016                excerpt.range.context.end.to_point(&excerpt.buffer)
3017                    + Point::new(down_line_count, 0),
3018                Bias::Left,
3019            );
3020            end_point.column = excerpt.buffer.line_len(end_point.row);
3021            excerpt.range.context.end = excerpt.buffer.anchor_after(end_point);
3022            excerpt.max_buffer_row = end_point.row;
3023
3024            excerpt.text_summary = excerpt
3025                .buffer
3026                .text_summary_for_range(excerpt.range.context.clone());
3027
3028            let new_start_offset = ExcerptDimension(new_excerpts.summary().text.len);
3029            let old_start_offset = cursor.start().1;
3030            let new_text_len = excerpt.text_summary.len;
3031            let edit = Edit {
3032                old: old_start_offset..old_start_offset + old_text_len,
3033                new: new_start_offset..new_start_offset + new_text_len,
3034            };
3035
3036            if let Some(last_edit) = edits.last_mut() {
3037                if last_edit.old.end == edit.old.start {
3038                    last_edit.old.end = edit.old.end;
3039                    last_edit.new.end = edit.new.end;
3040                } else {
3041                    edits.push(edit);
3042                }
3043            } else {
3044                edits.push(edit);
3045            }
3046
3047            new_excerpts.push(excerpt, ());
3048
3049            cursor.next();
3050        }
3051
3052        new_excerpts.append(cursor.suffix(), ());
3053
3054        drop(cursor);
3055        snapshot.excerpts = new_excerpts;
3056
3057        let edits = Self::sync_diff_transforms(&mut snapshot, edits, DiffChangeKind::BufferEdited);
3058        if !edits.is_empty() {
3059            self.subscriptions.publish(edits);
3060        }
3061        cx.emit(Event::Edited {
3062            edited_buffer: None,
3063        });
3064        cx.emit(Event::ExcerptsExpanded { ids });
3065        cx.notify();
3066    }
3067
3068    #[ztracing::instrument(skip_all)]
3069    fn sync(&self, cx: &App) {
3070        let changed = self.buffer_changed_since_sync.replace(false);
3071        if !changed {
3072            return;
3073        }
3074        let edits = Self::sync_from_buffer_changes(
3075            &mut self.snapshot.borrow_mut(),
3076            &self.buffers,
3077            &self.diffs,
3078            cx,
3079        );
3080        if !edits.is_empty() {
3081            self.subscriptions.publish(edits);
3082        }
3083    }
3084
3085    fn sync_mut(&mut self, cx: &App) {
3086        let changed = self.buffer_changed_since_sync.replace(false);
3087        if !changed {
3088            return;
3089        }
3090        let edits =
3091            Self::sync_from_buffer_changes(self.snapshot.get_mut(), &self.buffers, &self.diffs, cx);
3092
3093        if !edits.is_empty() {
3094            self.subscriptions.publish(edits);
3095        }
3096    }
3097
3098    fn sync_from_buffer_changes(
3099        snapshot: &mut MultiBufferSnapshot,
3100        buffers: &BTreeMap<BufferId, BufferState>,
3101        diffs: &HashMap<BufferId, DiffState>,
3102        cx: &App,
3103    ) -> Vec<Edit<MultiBufferOffset>> {
3104        let MultiBufferSnapshot {
3105            excerpts,
3106            buffer_locators: _,
3107            diffs: buffer_diff,
3108            diff_transforms: _,
3109            non_text_state_update_count,
3110            edit_count,
3111            is_dirty,
3112            has_deleted_file,
3113            has_conflict,
3114            has_inverted_diff: _,
3115            singleton: _,
3116            excerpt_ids: _,
3117            replaced_excerpts: _,
3118            trailing_excerpt_update_count: _,
3119            all_diff_hunks_expanded: _,
3120            show_deleted_hunks: _,
3121            use_extended_diff_range: _,
3122            show_headers: _,
3123        } = snapshot;
3124        *is_dirty = false;
3125        *has_deleted_file = false;
3126        *has_conflict = false;
3127
3128        if !diffs.is_empty() {
3129            let mut diffs_to_add = Vec::new();
3130            for (id, diff) in diffs {
3131                // For inverted diffs, we excerpt the diff base texts in the multibuffer
3132                // and use the diff hunk base text ranges to compute diff transforms.
3133                // Those base text ranges are usize, so make sure if the base text changed
3134                // we also update the diff snapshot so that we don't use stale offsets
3135                if buffer_diff.get(id).is_none_or(|existing_diff| {
3136                    if existing_diff.main_buffer.is_none() {
3137                        return false;
3138                    }
3139                    let base_text = diff.diff.read(cx).base_text_buffer().read(cx);
3140                    base_text.remote_id() != existing_diff.base_text().remote_id()
3141                        || base_text
3142                            .version()
3143                            .changed_since(existing_diff.base_text().version())
3144                }) {
3145                    if diffs_to_add.capacity() == 0 {
3146                        // we'd rather overallocate than reallocate as buffer diffs are quite big
3147                        // meaning re-allocations will be fairly expensive
3148                        diffs_to_add.reserve(diffs.len());
3149                    }
3150                    diffs_to_add.push((*id, diff.snapshot(cx)));
3151                }
3152            }
3153            buffer_diff.extend(diffs_to_add);
3154        }
3155
3156        let mut excerpts_to_edit = Vec::new();
3157        let mut non_text_state_updated = false;
3158        let mut edited = false;
3159        for buffer_state in buffers.values() {
3160            let buffer = buffer_state.buffer.read(cx);
3161            let version = buffer.version();
3162            let non_text_state_update_count = buffer.non_text_state_update_count();
3163
3164            let buffer_edited = version.changed_since(&buffer_state.last_version.borrow());
3165            let buffer_non_text_state_updated =
3166                non_text_state_update_count > buffer_state.last_non_text_state_update_count.get();
3167            if buffer_edited || buffer_non_text_state_updated {
3168                *buffer_state.last_version.borrow_mut() = version;
3169                buffer_state
3170                    .last_non_text_state_update_count
3171                    .set(non_text_state_update_count);
3172                excerpts_to_edit.extend(
3173                    buffer_state
3174                        .excerpts
3175                        .iter()
3176                        .map(|locator| (locator, buffer_state.buffer.clone(), buffer_edited)),
3177                );
3178            }
3179
3180            edited |= buffer_edited;
3181            non_text_state_updated |= buffer_non_text_state_updated;
3182            *is_dirty |= buffer.is_dirty();
3183            *has_deleted_file |= buffer
3184                .file()
3185                .is_some_and(|file| file.disk_state().is_deleted());
3186            *has_conflict |= buffer.has_conflict();
3187        }
3188        if edited {
3189            *edit_count += 1;
3190        }
3191        if non_text_state_updated {
3192            *non_text_state_update_count += 1;
3193        }
3194
3195        excerpts_to_edit.sort_unstable_by_key(|&(locator, _, _)| locator);
3196
3197        let mut edits = Vec::new();
3198        let mut new_excerpts = SumTree::default();
3199        let mut cursor = excerpts.cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
3200
3201        for (locator, buffer, buffer_edited) in excerpts_to_edit {
3202            new_excerpts.append(cursor.slice(&Some(locator), Bias::Left), ());
3203            let old_excerpt = cursor.item().unwrap();
3204            let buffer = buffer.read(cx);
3205            let buffer_id = buffer.remote_id();
3206            let mut new_excerpt;
3207            if buffer_edited {
3208                edits.extend(
3209                    buffer
3210                        .edits_since_in_range::<usize>(
3211                            old_excerpt.buffer.version(),
3212                            old_excerpt.range.context.clone(),
3213                        )
3214                        .map(|edit| {
3215                            let excerpt_old_start = cursor.start().1;
3216                            let excerpt_new_start =
3217                                ExcerptDimension(new_excerpts.summary().text.len);
3218                            let old_start = excerpt_old_start + edit.old.start;
3219                            let old_end = excerpt_old_start + edit.old.end;
3220                            let new_start = excerpt_new_start + edit.new.start;
3221                            let new_end = excerpt_new_start + edit.new.end;
3222                            Edit {
3223                                old: old_start..old_end,
3224                                new: new_start..new_end,
3225                            }
3226                        }),
3227                );
3228
3229                new_excerpt = Excerpt::new(
3230                    old_excerpt.id,
3231                    locator.clone(),
3232                    buffer_id,
3233                    Arc::new(buffer.snapshot()),
3234                    old_excerpt.range.clone(),
3235                    old_excerpt.has_trailing_newline,
3236                );
3237            } else {
3238                new_excerpt = old_excerpt.clone();
3239                new_excerpt.buffer = Arc::new(buffer.snapshot());
3240            }
3241
3242            new_excerpts.push(new_excerpt, ());
3243            cursor.next();
3244        }
3245        new_excerpts.append(cursor.suffix(), ());
3246
3247        drop(cursor);
3248        *excerpts = new_excerpts;
3249
3250        Self::sync_diff_transforms(snapshot, edits, DiffChangeKind::BufferEdited)
3251    }
3252
3253    fn sync_diff_transforms(
3254        snapshot: &mut MultiBufferSnapshot,
3255        excerpt_edits: Vec<text::Edit<ExcerptOffset>>,
3256        change_kind: DiffChangeKind,
3257    ) -> Vec<Edit<MultiBufferOffset>> {
3258        if excerpt_edits.is_empty() {
3259            return vec![];
3260        }
3261
3262        let mut excerpts = snapshot.excerpts.cursor::<ExcerptOffset>(());
3263        let mut old_diff_transforms = snapshot
3264            .diff_transforms
3265            .cursor::<Dimensions<ExcerptOffset, MultiBufferOffset>>(());
3266        let mut new_diff_transforms = SumTree::default();
3267        let mut old_expanded_hunks = HashSet::default();
3268        let mut output_edits = Vec::new();
3269        let mut output_delta = 0_isize;
3270        let mut at_transform_boundary = true;
3271        let mut end_of_current_insert = None;
3272
3273        let mut excerpt_edits = excerpt_edits.into_iter().peekable();
3274        while let Some(edit) = excerpt_edits.next() {
3275            excerpts.seek_forward(&edit.new.start, Bias::Right);
3276            if excerpts.item().is_none() && *excerpts.start() == edit.new.start {
3277                excerpts.prev();
3278            }
3279
3280            // Keep any transforms that are before the edit.
3281            if at_transform_boundary {
3282                at_transform_boundary = false;
3283                let transforms_before_edit = old_diff_transforms.slice(&edit.old.start, Bias::Left);
3284                Self::append_diff_transforms(&mut new_diff_transforms, transforms_before_edit);
3285                if let Some(transform) = old_diff_transforms.item()
3286                    && old_diff_transforms.end().0 == edit.old.start
3287                    && old_diff_transforms.start().0 < edit.old.start
3288                {
3289                    Self::push_diff_transform(&mut new_diff_transforms, transform.clone());
3290                    old_diff_transforms.next();
3291                }
3292            }
3293
3294            // Compute the start of the edit in output coordinates.
3295            let edit_start_overshoot = edit.old.start - old_diff_transforms.start().0;
3296            let edit_old_start = old_diff_transforms.start().1 + edit_start_overshoot;
3297            let edit_new_start =
3298                MultiBufferOffset((edit_old_start.0 as isize + output_delta) as usize);
3299
3300            let changed_diff_hunks = Self::recompute_diff_transforms_for_edit(
3301                &edit,
3302                &mut excerpts,
3303                &mut old_diff_transforms,
3304                &mut new_diff_transforms,
3305                &mut end_of_current_insert,
3306                &mut old_expanded_hunks,
3307                snapshot,
3308                change_kind,
3309            );
3310
3311            // Compute the end of the edit in output coordinates.
3312            let edit_old_end_overshoot = edit.old.end - old_diff_transforms.start().0;
3313            let edit_new_end_overshoot = edit.new.end - new_diff_transforms.summary().excerpt_len();
3314            let edit_old_end = old_diff_transforms.start().1 + edit_old_end_overshoot;
3315            let edit_new_end = new_diff_transforms.summary().output.len + edit_new_end_overshoot;
3316            let output_edit = Edit {
3317                old: edit_old_start..edit_old_end,
3318                new: edit_new_start..edit_new_end,
3319            };
3320
3321            output_delta += (output_edit.new.end - output_edit.new.start) as isize;
3322            output_delta -= (output_edit.old.end - output_edit.old.start) as isize;
3323            if changed_diff_hunks || matches!(change_kind, DiffChangeKind::BufferEdited) {
3324                output_edits.push(output_edit);
3325            }
3326
3327            // If this is the last edit that intersects the current diff transform,
3328            // then recreate the content up to the end of this transform, to prepare
3329            // for reusing additional slices of the old transforms.
3330            if excerpt_edits
3331                .peek()
3332                .is_none_or(|next_edit| next_edit.old.start >= old_diff_transforms.end().0)
3333            {
3334                let keep_next_old_transform = (old_diff_transforms.start().0 >= edit.old.end)
3335                    && match old_diff_transforms.item() {
3336                        Some(DiffTransform::BufferContent {
3337                            inserted_hunk_info: Some(hunk),
3338                            ..
3339                        }) => excerpts.item().is_some_and(|excerpt| {
3340                            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id)
3341                                && diff.main_buffer.is_some()
3342                            {
3343                                return true;
3344                            }
3345                            hunk.hunk_start_anchor.is_valid(&excerpt.buffer)
3346                        }),
3347                        _ => true,
3348                    };
3349
3350                let mut excerpt_offset = edit.new.end;
3351                if !keep_next_old_transform {
3352                    excerpt_offset += old_diff_transforms.end().0 - edit.old.end;
3353                    old_diff_transforms.next();
3354                }
3355
3356                old_expanded_hunks.clear();
3357                Self::push_buffer_content_transform(
3358                    snapshot,
3359                    &mut new_diff_transforms,
3360                    excerpt_offset,
3361                    end_of_current_insert,
3362                );
3363                at_transform_boundary = true;
3364            }
3365        }
3366
3367        // Keep any transforms that are after the last edit.
3368        Self::append_diff_transforms(&mut new_diff_transforms, old_diff_transforms.suffix());
3369
3370        // Ensure there's always at least one buffer content transform.
3371        if new_diff_transforms.is_empty() {
3372            new_diff_transforms.push(
3373                DiffTransform::BufferContent {
3374                    summary: Default::default(),
3375                    inserted_hunk_info: None,
3376                },
3377                (),
3378            );
3379        }
3380
3381        drop(old_diff_transforms);
3382        drop(excerpts);
3383        snapshot.diff_transforms = new_diff_transforms;
3384        snapshot.edit_count += 1;
3385
3386        #[cfg(any(test, feature = "test-support"))]
3387        snapshot.check_invariants();
3388        output_edits
3389    }
3390
3391    fn recompute_diff_transforms_for_edit(
3392        edit: &Edit<ExcerptOffset>,
3393        excerpts: &mut Cursor<Excerpt, ExcerptOffset>,
3394        old_diff_transforms: &mut Cursor<
3395            DiffTransform,
3396            Dimensions<ExcerptOffset, MultiBufferOffset>,
3397        >,
3398        new_diff_transforms: &mut SumTree<DiffTransform>,
3399        end_of_current_insert: &mut Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3400        old_expanded_hunks: &mut HashSet<DiffTransformHunkInfo>,
3401        snapshot: &MultiBufferSnapshot,
3402        change_kind: DiffChangeKind,
3403    ) -> bool {
3404        log::trace!(
3405            "recomputing diff transform for edit {:?} => {:?}",
3406            edit.old.start..edit.old.end,
3407            edit.new.start..edit.new.end
3408        );
3409
3410        // Record which hunks were previously expanded.
3411        while let Some(item) = old_diff_transforms.item() {
3412            if let Some(hunk_info) = item.hunk_info() {
3413                log::trace!(
3414                    "previously expanded hunk at {:?}",
3415                    old_diff_transforms.start()
3416                );
3417                old_expanded_hunks.insert(hunk_info);
3418            }
3419            if old_diff_transforms.end().0 > edit.old.end {
3420                break;
3421            }
3422            old_diff_transforms.next();
3423        }
3424
3425        // Avoid querying diff hunks if there's no possibility of hunks being expanded.
3426        // For inverted diffs, hunks are always shown, so we can't skip this.
3427        let all_diff_hunks_expanded = snapshot.all_diff_hunks_expanded;
3428        if old_expanded_hunks.is_empty()
3429            && change_kind == DiffChangeKind::BufferEdited
3430            && !all_diff_hunks_expanded
3431            && !snapshot.has_inverted_diff
3432        {
3433            return false;
3434        }
3435
3436        // Visit each excerpt that intersects the edit.
3437        let mut did_expand_hunks = false;
3438        while let Some(excerpt) = excerpts.item() {
3439            // Recompute the expanded hunks in the portion of the excerpt that
3440            // intersects the edit.
3441            if let Some(diff) = snapshot.diffs.get(&excerpt.buffer_id) {
3442                let buffer = &excerpt.buffer;
3443                let excerpt_start = *excerpts.start();
3444                let excerpt_end = excerpt_start + excerpt.text_summary.len;
3445                let excerpt_buffer_start = excerpt.range.context.start.to_offset(buffer);
3446                let excerpt_buffer_end = excerpt_buffer_start + excerpt.text_summary.len;
3447                let edit_buffer_start =
3448                    excerpt_buffer_start + edit.new.start.saturating_sub(excerpt_start);
3449                let edit_buffer_end =
3450                    excerpt_buffer_start + edit.new.end.saturating_sub(excerpt_start);
3451                let edit_buffer_end = edit_buffer_end.min(excerpt_buffer_end);
3452
3453                if let Some(main_buffer) = &diff.main_buffer {
3454                    for hunk in diff.hunks_intersecting_base_text_range(
3455                        edit_buffer_start..edit_buffer_end,
3456                        main_buffer,
3457                    ) {
3458                        did_expand_hunks = true;
3459                        let hunk_buffer_range = hunk.diff_base_byte_range.clone();
3460                        if hunk_buffer_range.start < excerpt_buffer_start {
3461                            log::trace!("skipping hunk that starts before excerpt");
3462                            continue;
3463                        }
3464                        hunk_buffer_range.end.to_point(&excerpt.buffer);
3465                        let hunk_excerpt_start = excerpt_start
3466                            + hunk_buffer_range.start.saturating_sub(excerpt_buffer_start);
3467                        let hunk_excerpt_end = excerpt_end
3468                            .min(excerpt_start + (hunk_buffer_range.end - excerpt_buffer_start));
3469                        Self::push_buffer_content_transform(
3470                            snapshot,
3471                            new_diff_transforms,
3472                            hunk_excerpt_start,
3473                            *end_of_current_insert,
3474                        );
3475                        if !hunk_buffer_range.is_empty() {
3476                            let hunk_info = DiffTransformHunkInfo {
3477                                excerpt_id: excerpt.id,
3478                                hunk_start_anchor: hunk.buffer_range.start,
3479                                hunk_secondary_status: hunk.secondary_status,
3480                                is_logically_deleted: true,
3481                            };
3482                            *end_of_current_insert =
3483                                Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3484                        }
3485                    }
3486                } else {
3487                    let edit_anchor_range = buffer.anchor_before(edit_buffer_start)
3488                        ..buffer.anchor_after(edit_buffer_end);
3489                    for hunk in diff.hunks_intersecting_range(edit_anchor_range, buffer) {
3490                        if hunk.is_created_file() && !all_diff_hunks_expanded {
3491                            continue;
3492                        }
3493
3494                        let hunk_buffer_range = hunk.buffer_range.to_offset(buffer);
3495                        if hunk_buffer_range.start < excerpt_buffer_start {
3496                            log::trace!("skipping hunk that starts before excerpt");
3497                            continue;
3498                        }
3499
3500                        let hunk_info = DiffTransformHunkInfo {
3501                            excerpt_id: excerpt.id,
3502                            hunk_start_anchor: hunk.buffer_range.start,
3503                            hunk_secondary_status: hunk.secondary_status,
3504                            is_logically_deleted: false,
3505                        };
3506
3507                        let hunk_excerpt_start = excerpt_start
3508                            + hunk_buffer_range.start.saturating_sub(excerpt_buffer_start);
3509                        let hunk_excerpt_end = excerpt_end
3510                            .min(excerpt_start + (hunk_buffer_range.end - excerpt_buffer_start));
3511
3512                        Self::push_buffer_content_transform(
3513                            snapshot,
3514                            new_diff_transforms,
3515                            hunk_excerpt_start,
3516                            *end_of_current_insert,
3517                        );
3518
3519                        // For every existing hunk, determine if it was previously expanded
3520                        // and if it should currently be expanded.
3521                        let was_previously_expanded = old_expanded_hunks.contains(&hunk_info);
3522                        let should_expand_hunk = match &change_kind {
3523                            DiffChangeKind::DiffUpdated { base_changed: true } => {
3524                                was_previously_expanded || all_diff_hunks_expanded
3525                            }
3526                            DiffChangeKind::ExpandOrCollapseHunks { expand } => {
3527                                let intersects = hunk_buffer_range.is_empty()
3528                                    || hunk_buffer_range.end > edit_buffer_start;
3529                                if *expand {
3530                                    intersects || was_previously_expanded || all_diff_hunks_expanded
3531                                } else {
3532                                    !intersects
3533                                        && (was_previously_expanded || all_diff_hunks_expanded)
3534                                }
3535                            }
3536                            _ => was_previously_expanded || all_diff_hunks_expanded,
3537                        };
3538
3539                        if should_expand_hunk {
3540                            did_expand_hunks = true;
3541                            log::trace!(
3542                                "expanding hunk {:?}, excerpt:{:?}",
3543                                hunk_excerpt_start..hunk_excerpt_end,
3544                                excerpt.id
3545                            );
3546
3547                            if !hunk.diff_base_byte_range.is_empty()
3548                                && hunk_buffer_range.start >= edit_buffer_start
3549                                && hunk_buffer_range.start <= excerpt_buffer_end
3550                                && snapshot.show_deleted_hunks
3551                            {
3552                                let base_text = diff.base_text();
3553                                let mut text_cursor =
3554                                    base_text.as_rope().cursor(hunk.diff_base_byte_range.start);
3555                                let mut base_text_summary = text_cursor
3556                                    .summary::<TextSummary>(hunk.diff_base_byte_range.end);
3557
3558                                let mut has_trailing_newline = false;
3559                                if base_text_summary.last_line_chars > 0 {
3560                                    base_text_summary += TextSummary::newline();
3561                                    has_trailing_newline = true;
3562                                }
3563
3564                                new_diff_transforms.push(
3565                                    DiffTransform::DeletedHunk {
3566                                        base_text_byte_range: hunk.diff_base_byte_range.clone(),
3567                                        summary: base_text_summary,
3568                                        buffer_id: excerpt.buffer_id,
3569                                        hunk_info,
3570                                        has_trailing_newline,
3571                                    },
3572                                    (),
3573                                );
3574                            }
3575
3576                            if !hunk_buffer_range.is_empty() {
3577                                *end_of_current_insert =
3578                                    Some((hunk_excerpt_end.min(excerpt_end), hunk_info));
3579                            }
3580                        }
3581                    }
3582                }
3583            }
3584
3585            if excerpts.end() <= edit.new.end {
3586                excerpts.next();
3587            } else {
3588                break;
3589            }
3590        }
3591
3592        did_expand_hunks || !old_expanded_hunks.is_empty()
3593    }
3594
3595    fn append_diff_transforms(
3596        new_transforms: &mut SumTree<DiffTransform>,
3597        subtree: SumTree<DiffTransform>,
3598    ) {
3599        if let Some(DiffTransform::BufferContent {
3600            inserted_hunk_info,
3601            summary,
3602        }) = subtree.first()
3603            && Self::extend_last_buffer_content_transform(
3604                new_transforms,
3605                *inserted_hunk_info,
3606                *summary,
3607            )
3608        {
3609            let mut cursor = subtree.cursor::<()>(());
3610            cursor.next();
3611            cursor.next();
3612            new_transforms.append(cursor.suffix(), ());
3613            return;
3614        }
3615        new_transforms.append(subtree, ());
3616    }
3617
3618    fn push_diff_transform(new_transforms: &mut SumTree<DiffTransform>, transform: DiffTransform) {
3619        if let DiffTransform::BufferContent {
3620            inserted_hunk_info: inserted_hunk_anchor,
3621            summary,
3622        } = transform
3623            && Self::extend_last_buffer_content_transform(
3624                new_transforms,
3625                inserted_hunk_anchor,
3626                summary,
3627            )
3628        {
3629            return;
3630        }
3631        new_transforms.push(transform, ());
3632    }
3633
3634    fn push_buffer_content_transform(
3635        old_snapshot: &MultiBufferSnapshot,
3636        new_transforms: &mut SumTree<DiffTransform>,
3637        end_offset: ExcerptOffset,
3638        current_inserted_hunk: Option<(ExcerptOffset, DiffTransformHunkInfo)>,
3639    ) {
3640        let inserted_region = current_inserted_hunk.map(|(insertion_end_offset, hunk_info)| {
3641            (end_offset.min(insertion_end_offset), Some(hunk_info))
3642        });
3643        let unchanged_region = [(end_offset, None)];
3644
3645        for (end_offset, inserted_hunk_info) in inserted_region.into_iter().chain(unchanged_region)
3646        {
3647            let start_offset = new_transforms.summary().excerpt_len();
3648            if end_offset <= start_offset {
3649                continue;
3650            }
3651            let summary_to_add = old_snapshot
3652                .text_summary_for_excerpt_offset_range::<MBTextSummary>(start_offset..end_offset);
3653
3654            if !Self::extend_last_buffer_content_transform(
3655                new_transforms,
3656                inserted_hunk_info,
3657                summary_to_add,
3658            ) {
3659                new_transforms.push(
3660                    DiffTransform::BufferContent {
3661                        summary: summary_to_add,
3662                        inserted_hunk_info,
3663                    },
3664                    (),
3665                )
3666            }
3667        }
3668    }
3669
3670    fn extend_last_buffer_content_transform(
3671        new_transforms: &mut SumTree<DiffTransform>,
3672        new_inserted_hunk_info: Option<DiffTransformHunkInfo>,
3673        summary_to_add: MBTextSummary,
3674    ) -> bool {
3675        let mut did_extend = false;
3676        new_transforms.update_last(
3677            |last_transform| {
3678                if let DiffTransform::BufferContent {
3679                    summary,
3680                    inserted_hunk_info: inserted_hunk_anchor,
3681                } = last_transform
3682                    && *inserted_hunk_anchor == new_inserted_hunk_info
3683                {
3684                    *summary += summary_to_add;
3685                    did_extend = true;
3686                }
3687            },
3688            (),
3689        );
3690        did_extend
3691    }
3692
3693    pub fn toggle_single_diff_hunk(&mut self, range: Range<Anchor>, cx: &mut Context<Self>) {
3694        let snapshot = self.snapshot(cx);
3695        let excerpt_id = range.end.excerpt_id;
3696        let point_range = range.to_point(&snapshot);
3697        let expand = !self.single_hunk_is_expanded(range, cx);
3698        let edits =
3699            self.expand_or_collapse_diff_hunks_inner([(point_range, excerpt_id)], expand, cx);
3700        if !edits.is_empty() {
3701            self.subscriptions.publish(edits);
3702        }
3703        cx.emit(Event::DiffHunksToggled);
3704        cx.emit(Event::Edited {
3705            edited_buffer: None,
3706        });
3707    }
3708}
3709
3710fn build_excerpt_ranges(
3711    ranges: impl IntoIterator<Item = Range<Point>>,
3712    context_line_count: u32,
3713    buffer_snapshot: &BufferSnapshot,
3714) -> Vec<ExcerptRange<Point>> {
3715    ranges
3716        .into_iter()
3717        .map(|range| {
3718            let start_row = range.start.row.saturating_sub(context_line_count);
3719            let start = Point::new(start_row, 0);
3720            let end_row = (range.end.row + context_line_count).min(buffer_snapshot.max_point().row);
3721            let end = Point::new(end_row, buffer_snapshot.line_len(end_row));
3722            ExcerptRange {
3723                context: start..end,
3724                primary: range,
3725            }
3726        })
3727        .collect()
3728}
3729
3730#[cfg(any(test, feature = "test-support"))]
3731impl MultiBuffer {
3732    pub fn build_simple(text: &str, cx: &mut gpui::App) -> Entity<Self> {
3733        let buffer = cx.new(|cx| Buffer::local(text, cx));
3734        cx.new(|cx| Self::singleton(buffer, cx))
3735    }
3736
3737    pub fn build_multi<const COUNT: usize>(
3738        excerpts: [(&str, Vec<Range<Point>>); COUNT],
3739        cx: &mut gpui::App,
3740    ) -> Entity<Self> {
3741        let multi = cx.new(|_| Self::new(Capability::ReadWrite));
3742        for (ix, (text, ranges)) in excerpts.into_iter().enumerate() {
3743            let buffer = cx.new(|cx| Buffer::local(text, cx));
3744            let snapshot = buffer.read(cx).snapshot();
3745            let excerpt_ranges = ranges
3746                .into_iter()
3747                .map(ExcerptRange::new)
3748                .collect::<Vec<_>>();
3749            multi.update(cx, |multi, cx| {
3750                multi.set_excerpt_ranges_for_path(
3751                    PathKey::sorted(ix as u64),
3752                    buffer,
3753                    &snapshot,
3754                    excerpt_ranges,
3755                    cx,
3756                )
3757            });
3758        }
3759
3760        multi
3761    }
3762
3763    pub fn build_from_buffer(buffer: Entity<Buffer>, cx: &mut gpui::App) -> Entity<Self> {
3764        cx.new(|cx| Self::singleton(buffer, cx))
3765    }
3766
3767    pub fn build_random(rng: &mut impl rand::Rng, cx: &mut gpui::App) -> Entity<Self> {
3768        cx.new(|cx| {
3769            let mut multibuffer = MultiBuffer::new(Capability::ReadWrite);
3770            let mutation_count = rng.random_range(1..=5);
3771            multibuffer.randomly_edit_excerpts(rng, mutation_count, cx);
3772            multibuffer
3773        })
3774    }
3775
3776    pub fn randomly_edit(
3777        &mut self,
3778        rng: &mut impl rand::Rng,
3779        edit_count: usize,
3780        cx: &mut Context<Self>,
3781    ) {
3782        use util::RandomCharIter;
3783
3784        let snapshot = self.read(cx);
3785        let mut edits: Vec<(Range<MultiBufferOffset>, Arc<str>)> = Vec::new();
3786        let mut last_end = None;
3787        for _ in 0..edit_count {
3788            if last_end.is_some_and(|last_end| last_end >= snapshot.len()) {
3789                break;
3790            }
3791
3792            let new_start = last_end.map_or(MultiBufferOffset::ZERO, |last_end| last_end + 1usize);
3793            let end =
3794                snapshot.clip_offset(rng.random_range(new_start..=snapshot.len()), Bias::Right);
3795            let start = snapshot.clip_offset(rng.random_range(new_start..=end), Bias::Right);
3796            last_end = Some(end);
3797
3798            let mut range = start..end;
3799            if rng.random_bool(0.2) {
3800                mem::swap(&mut range.start, &mut range.end);
3801            }
3802
3803            let new_text_len = rng.random_range(0..10);
3804            let new_text: String = RandomCharIter::new(&mut *rng).take(new_text_len).collect();
3805
3806            edits.push((range, new_text.into()));
3807        }
3808        log::info!("mutating multi-buffer with {:?}", edits);
3809        drop(snapshot);
3810
3811        self.edit(edits, None, cx);
3812    }
3813
3814    pub fn randomly_edit_excerpts(
3815        &mut self,
3816        rng: &mut impl rand::Rng,
3817        mutation_count: usize,
3818        cx: &mut Context<Self>,
3819    ) {
3820        use rand::prelude::*;
3821        use std::env;
3822        use util::RandomCharIter;
3823
3824        let max_excerpts = env::var("MAX_EXCERPTS")
3825            .map(|i| i.parse().expect("invalid `MAX_EXCERPTS` variable"))
3826            .unwrap_or(5);
3827
3828        let mut buffers = Vec::new();
3829        for _ in 0..mutation_count {
3830            if rng.random_bool(0.05) {
3831                log::info!("Clearing multi-buffer");
3832                self.clear(cx);
3833                continue;
3834            } else if rng.random_bool(0.1) && !self.excerpt_ids().is_empty() {
3835                let ids = self.excerpt_ids();
3836                let mut excerpts = HashSet::default();
3837                for _ in 0..rng.random_range(0..ids.len()) {
3838                    excerpts.extend(ids.choose(rng).copied());
3839                }
3840
3841                let line_count = rng.random_range(0..5);
3842
3843                log::info!("Expanding excerpts {excerpts:?} by {line_count} lines");
3844
3845                self.expand_excerpts(
3846                    excerpts.iter().cloned(),
3847                    line_count,
3848                    ExpandExcerptDirection::UpAndDown,
3849                    cx,
3850                );
3851                continue;
3852            }
3853
3854            let excerpt_ids = self.excerpt_ids();
3855            if excerpt_ids.is_empty() || (rng.random() && excerpt_ids.len() < max_excerpts) {
3856                let buffer_handle = if rng.random() || self.buffers.is_empty() {
3857                    let text = RandomCharIter::new(&mut *rng).take(10).collect::<String>();
3858                    buffers.push(cx.new(|cx| Buffer::local(text, cx)));
3859                    let buffer = buffers.last().unwrap().read(cx);
3860                    log::info!(
3861                        "Creating new buffer {} with text: {:?}",
3862                        buffer.remote_id(),
3863                        buffer.text()
3864                    );
3865                    buffers.last().unwrap().clone()
3866                } else {
3867                    self.buffers.values().choose(rng).unwrap().buffer.clone()
3868                };
3869
3870                let buffer = buffer_handle.read(cx);
3871                let buffer_text = buffer.text();
3872                let ranges = (0..rng.random_range(0..5))
3873                    .map(|_| {
3874                        let end_ix =
3875                            buffer.clip_offset(rng.random_range(0..=buffer.len()), Bias::Right);
3876                        let start_ix = buffer.clip_offset(rng.random_range(0..=end_ix), Bias::Left);
3877                        ExcerptRange::new(start_ix..end_ix)
3878                    })
3879                    .collect::<Vec<_>>();
3880                log::info!(
3881                    "Inserting excerpts from buffer {} and ranges {:?}: {:?}",
3882                    buffer_handle.read(cx).remote_id(),
3883                    ranges.iter().map(|r| &r.context).collect::<Vec<_>>(),
3884                    ranges
3885                        .iter()
3886                        .map(|r| &buffer_text[r.context.clone()])
3887                        .collect::<Vec<_>>()
3888                );
3889
3890                let excerpt_id =
3891                    self.insert_excerpts_after(ExcerptId::max(), buffer_handle, ranges, cx);
3892                log::info!("Inserted with ids: {:?}", excerpt_id);
3893            } else {
3894                let remove_count = rng.random_range(1..=excerpt_ids.len());
3895                let mut excerpts_to_remove = excerpt_ids
3896                    .choose_multiple(rng, remove_count)
3897                    .cloned()
3898                    .collect::<Vec<_>>();
3899                let snapshot = self.snapshot.borrow();
3900                excerpts_to_remove.sort_unstable_by(|a, b| a.cmp(b, &snapshot));
3901                drop(snapshot);
3902                log::info!("Removing excerpts {:?}", excerpts_to_remove);
3903                self.remove_excerpts(excerpts_to_remove, cx);
3904            }
3905        }
3906    }
3907
3908    pub fn randomly_mutate(
3909        &mut self,
3910        rng: &mut impl rand::Rng,
3911        mutation_count: usize,
3912        cx: &mut Context<Self>,
3913    ) {
3914        use rand::prelude::*;
3915
3916        if rng.random_bool(0.7) || self.singleton {
3917            let buffer = self
3918                .buffers
3919                .values()
3920                .choose(rng)
3921                .map(|state| state.buffer.clone());
3922
3923            if let Some(buffer) = buffer {
3924                buffer.update(cx, |buffer, cx| {
3925                    if rng.random() {
3926                        buffer.randomly_edit(rng, mutation_count, cx);
3927                    } else {
3928                        buffer.randomly_undo_redo(rng, cx);
3929                    }
3930                });
3931            } else {
3932                self.randomly_edit(rng, mutation_count, cx);
3933            }
3934        } else {
3935            self.randomly_edit_excerpts(rng, mutation_count, cx);
3936        }
3937
3938        self.check_invariants(cx);
3939    }
3940
3941    fn check_invariants(&self, cx: &App) {
3942        self.read(cx).check_invariants();
3943    }
3944}
3945
3946impl EventEmitter<Event> for MultiBuffer {}
3947
3948impl MultiBufferSnapshot {
3949    pub fn text(&self) -> String {
3950        self.chunks(MultiBufferOffset::ZERO..self.len(), false)
3951            .map(|chunk| chunk.text)
3952            .collect()
3953    }
3954
3955    pub fn reversed_chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3956        self.reversed_chunks_in_range(MultiBufferOffset::ZERO..position.to_offset(self))
3957            .flat_map(|c| c.chars().rev())
3958    }
3959
3960    fn reversed_chunks_in_range(
3961        &self,
3962        range: Range<MultiBufferOffset>,
3963    ) -> ReversedMultiBufferChunks<'_> {
3964        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
3965        cursor.seek(&range.end);
3966        let current_chunks = cursor.region().as_ref().map(|region| {
3967            let start_overshoot = range.start.saturating_sub(region.range.start);
3968            let end_overshoot = range.end - region.range.start;
3969            let end = (region.buffer_range.start + end_overshoot).min(region.buffer_range.end);
3970            let start = region.buffer_range.start + start_overshoot;
3971            region.buffer.reversed_chunks_in_range(start..end)
3972        });
3973        ReversedMultiBufferChunks {
3974            cursor,
3975            current_chunks,
3976            start: range.start,
3977            offset: range.end,
3978        }
3979    }
3980
3981    pub fn chars_at<T: ToOffset>(&self, position: T) -> impl Iterator<Item = char> + '_ {
3982        let offset = position.to_offset(self);
3983        self.text_for_range(offset..self.len())
3984            .flat_map(|chunk| chunk.chars())
3985    }
3986
3987    pub fn text_for_range<T: ToOffset>(&self, range: Range<T>) -> impl Iterator<Item = &str> + '_ {
3988        self.chunks(range, false).map(|chunk| chunk.text)
3989    }
3990
3991    pub fn is_line_blank(&self, row: MultiBufferRow) -> bool {
3992        self.text_for_range(Point::new(row.0, 0)..Point::new(row.0, self.line_len(row)))
3993            .all(|chunk| chunk.matches(|c: char| !c.is_whitespace()).next().is_none())
3994    }
3995
3996    pub fn contains_str_at<T>(&self, position: T, needle: &str) -> bool
3997    where
3998        T: ToOffset,
3999    {
4000        let position = position.to_offset(self);
4001        position == self.clip_offset(position, Bias::Left)
4002            && self
4003                .bytes_in_range(position..self.len())
4004                .flatten()
4005                .copied()
4006                .take(needle.len())
4007                .eq(needle.bytes())
4008    }
4009
4010    pub fn diff_hunks(&self) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
4011        self.diff_hunks_in_range(Anchor::min()..Anchor::max())
4012    }
4013
4014    pub fn diff_hunks_in_range<T: ToPoint>(
4015        &self,
4016        range: Range<T>,
4017    ) -> impl Iterator<Item = MultiBufferDiffHunk> + '_ {
4018        let query_range = range.start.to_point(self)..range.end.to_point(self);
4019        self.lift_buffer_metadata(query_range.clone(), move |buffer, buffer_range| {
4020            let diff = self.diffs.get(&buffer.remote_id())?;
4021            let iter = if let Some(main_buffer) = &diff.main_buffer {
4022                let buffer_start = buffer.point_to_offset(buffer_range.start);
4023                let buffer_end = buffer.point_to_offset(buffer_range.end);
4024                itertools::Either::Left(
4025                    diff.hunks_intersecting_base_text_range(buffer_start..buffer_end, main_buffer)
4026                        .map(move |hunk| (hunk, buffer, true)),
4027                )
4028            } else {
4029                let buffer_start = buffer.anchor_before(buffer_range.start);
4030                let buffer_end = buffer.anchor_after(buffer_range.end);
4031                itertools::Either::Right(
4032                    diff.hunks_intersecting_range(buffer_start..buffer_end, buffer)
4033                        .map(move |hunk| (hunk, buffer, false)),
4034                )
4035            };
4036            Some(iter.filter_map(|(hunk, buffer, is_inverted)| {
4037                if hunk.is_created_file() && !self.all_diff_hunks_expanded {
4038                    return None;
4039                }
4040                let range = if is_inverted {
4041                    hunk.diff_base_byte_range.to_point(&buffer)
4042                } else {
4043                    hunk.range.clone()
4044                };
4045                Some((range, (hunk, is_inverted)))
4046            }))
4047        })
4048        .filter_map(move |(range, (hunk, is_inverted), excerpt)| {
4049            if range.start != range.end && range.end == query_range.start && !hunk.range.is_empty()
4050            {
4051                return None;
4052            }
4053            let end_row = if range.end.column == 0 {
4054                range.end.row
4055            } else {
4056                range.end.row + 1
4057            };
4058
4059            let word_diffs =
4060                (!hunk.base_word_diffs.is_empty() || !hunk.buffer_word_diffs.is_empty())
4061                    .then(|| {
4062                        let mut word_diffs = Vec::new();
4063
4064                        if self.show_deleted_hunks || is_inverted {
4065                            let hunk_start_offset = if is_inverted {
4066                                Anchor::in_buffer(
4067                                    excerpt.id,
4068                                    excerpt.buffer.anchor_after(hunk.diff_base_byte_range.start),
4069                                )
4070                                .to_offset(self)
4071                            } else {
4072                                Anchor::in_buffer(excerpt.id, hunk.buffer_range.start)
4073                                    .to_offset(self)
4074                            };
4075
4076                            word_diffs.extend(hunk.base_word_diffs.iter().map(|diff| {
4077                                hunk_start_offset + diff.start..hunk_start_offset + diff.end
4078                            }));
4079                        }
4080
4081                        if !is_inverted {
4082                            word_diffs.extend(hunk.buffer_word_diffs.into_iter().map(|diff| {
4083                                Anchor::range_in_buffer(excerpt.id, diff).to_offset(self)
4084                            }));
4085                        }
4086                        word_diffs
4087                    })
4088                    .unwrap_or_default();
4089
4090            let buffer_range = if is_inverted {
4091                excerpt.buffer.anchor_after(hunk.diff_base_byte_range.start)
4092                    ..excerpt.buffer.anchor_before(hunk.diff_base_byte_range.end)
4093            } else {
4094                hunk.buffer_range.clone()
4095            };
4096            let status_kind = if hunk.buffer_range.start == hunk.buffer_range.end {
4097                DiffHunkStatusKind::Deleted
4098            } else if hunk.diff_base_byte_range.is_empty() {
4099                DiffHunkStatusKind::Added
4100            } else {
4101                DiffHunkStatusKind::Modified
4102            };
4103            Some(MultiBufferDiffHunk {
4104                row_range: MultiBufferRow(range.start.row)..MultiBufferRow(end_row),
4105                buffer_id: excerpt.buffer_id,
4106                excerpt_id: excerpt.id,
4107                buffer_range,
4108                word_diffs,
4109                diff_base_byte_range: BufferOffset(hunk.diff_base_byte_range.start)
4110                    ..BufferOffset(hunk.diff_base_byte_range.end),
4111                status: DiffHunkStatus {
4112                    kind: status_kind,
4113                    secondary: hunk.secondary_status,
4114                },
4115            })
4116        })
4117    }
4118
4119    fn excerpts_for_range<T: ToOffset>(
4120        &self,
4121        range: Range<T>,
4122    ) -> impl Iterator<Item = &Excerpt> + '_ {
4123        let range = range.start.to_offset(self)..range.end.to_offset(self);
4124        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
4125        cursor.seek(&range.start);
4126        std::iter::from_fn(move || {
4127            let region = cursor.region()?;
4128            if region.range.start > range.end
4129                || region.range.start == range.end && region.range.start > range.start
4130            {
4131                return None;
4132            }
4133            let excerpt = region.excerpt;
4134            cursor.next_excerpt_forwards();
4135            Some(excerpt)
4136        })
4137    }
4138
4139    pub fn excerpt_ids_for_range<T: ToOffset>(
4140        &self,
4141        range: Range<T>,
4142    ) -> impl Iterator<Item = ExcerptId> + '_ {
4143        self.excerpts_for_range(range).map(|excerpt| excerpt.id)
4144    }
4145
4146    pub fn buffer_ids_for_range<T: ToOffset>(
4147        &self,
4148        range: Range<T>,
4149    ) -> impl Iterator<Item = BufferId> + '_ {
4150        self.excerpts_for_range(range)
4151            .map(|excerpt| excerpt.buffer_id)
4152    }
4153
4154    /// Resolves the given [`text::Anchor`]s to [`crate::Anchor`]s if the anchor is within a visible excerpt.
4155    ///
4156    /// The passed in anchors must be ordered.
4157    pub fn text_anchors_to_visible_anchors(
4158        &self,
4159        anchors: impl IntoIterator<Item = text::Anchor>,
4160    ) -> Vec<Option<Anchor>> {
4161        let anchors = anchors.into_iter();
4162        let mut result = Vec::with_capacity(anchors.size_hint().0);
4163        let mut anchors = anchors.peekable();
4164        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
4165        'anchors: while let Some(anchor) = anchors.peek() {
4166            let Some(buffer_id) = anchor.buffer_id else {
4167                anchors.next();
4168                result.push(None);
4169                continue 'anchors;
4170            };
4171            let mut same_buffer_anchors =
4172                anchors.peeking_take_while(|a| a.buffer_id.is_some_and(|b| buffer_id == b));
4173
4174            if let Some(locators) = self.buffer_locators.get(&buffer_id) {
4175                let Some(mut next) = same_buffer_anchors.next() else {
4176                    continue 'anchors;
4177                };
4178                'excerpts: for locator in locators.iter() {
4179                    if cursor.seek_forward(&Some(locator), Bias::Left)
4180                        && let Some(excerpt) = cursor.item()
4181                    {
4182                        loop {
4183                            // anchor is before the first excerpt
4184                            if excerpt
4185                                .range
4186                                .context
4187                                .start
4188                                .cmp(&next, &excerpt.buffer)
4189                                .is_gt()
4190                            {
4191                                // so we skip it and try the next anchor
4192                                result.push(None);
4193                                match same_buffer_anchors.next() {
4194                                    Some(anchor) => next = anchor,
4195                                    None => continue 'anchors,
4196                                }
4197                            // anchor is within the excerpt
4198                            } else if excerpt
4199                                .range
4200                                .context
4201                                .end
4202                                .cmp(&next, &excerpt.buffer)
4203                                .is_ge()
4204                            {
4205                                // record it and all following anchors that are within
4206                                result.push(Some(Anchor::in_buffer(excerpt.id, next)));
4207                                result.extend(
4208                                    same_buffer_anchors
4209                                        .peeking_take_while(|a| {
4210                                            excerpt
4211                                                .range
4212                                                .context
4213                                                .end
4214                                                .cmp(a, &excerpt.buffer)
4215                                                .is_ge()
4216                                        })
4217                                        .map(|a| Some(Anchor::in_buffer(excerpt.id, a))),
4218                                );
4219                                match same_buffer_anchors.next() {
4220                                    Some(anchor) => next = anchor,
4221                                    None => continue 'anchors,
4222                                }
4223                            // anchor is after the excerpt, try the next one
4224                            } else {
4225                                continue 'excerpts;
4226                            }
4227                        }
4228                    }
4229                }
4230                // account for `next`
4231                result.push(None);
4232            }
4233            result.extend(same_buffer_anchors.map(|_| None));
4234        }
4235
4236        result
4237    }
4238
4239    pub fn ranges_to_buffer_ranges<T: ToOffset>(
4240        &self,
4241        ranges: impl Iterator<Item = Range<T>>,
4242    ) -> impl Iterator<Item = (&BufferSnapshot, Range<BufferOffset>, ExcerptId)> {
4243        ranges.flat_map(|range| {
4244            self.range_to_buffer_ranges((Bound::Included(range.start), Bound::Included(range.end)))
4245                .into_iter()
4246        })
4247    }
4248
4249    pub fn range_to_buffer_ranges<R, T>(
4250        &self,
4251        range: R,
4252    ) -> Vec<(&BufferSnapshot, Range<BufferOffset>, ExcerptId)>
4253    where
4254        R: RangeBounds<T>,
4255        T: ToOffset,
4256    {
4257        self.range_to_buffer_ranges_with_context(range)
4258            .into_iter()
4259            .map(|(buffer, range, id, _context)| (buffer, range, id))
4260            .collect()
4261    }
4262
4263    pub fn range_to_buffer_ranges_with_context<R, T>(
4264        &self,
4265        range: R,
4266    ) -> Vec<(
4267        &BufferSnapshot,
4268        Range<BufferOffset>,
4269        ExcerptId,
4270        Range<text::Anchor>,
4271    )>
4272    where
4273        R: RangeBounds<T>,
4274        T: ToOffset,
4275    {
4276        let start = match range.start_bound() {
4277            Bound::Included(start) => start.to_offset(self),
4278            Bound::Excluded(_) => panic!("excluded start bound not supported"),
4279            Bound::Unbounded => MultiBufferOffset::ZERO,
4280        };
4281        let end_bound = match range.end_bound() {
4282            Bound::Included(end) => Bound::Included(end.to_offset(self)),
4283            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
4284            Bound::Unbounded => Bound::Unbounded,
4285        };
4286        let bounds = (Bound::Included(start), end_bound);
4287
4288        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
4289        cursor.seek(&start);
4290
4291        let mut result: Vec<(
4292            &BufferSnapshot,
4293            Range<BufferOffset>,
4294            ExcerptId,
4295            Range<text::Anchor>,
4296        )> = Vec::new();
4297        while let Some(region) = cursor.region() {
4298            let dominated_by_end_bound = match end_bound {
4299                Bound::Included(end) => region.range.start > end,
4300                Bound::Excluded(end) => region.range.start >= end,
4301                Bound::Unbounded => false,
4302            };
4303            if dominated_by_end_bound {
4304                break;
4305            }
4306            if region.is_main_buffer {
4307                let start_overshoot = start.saturating_sub(region.range.start);
4308                let end_offset = match end_bound {
4309                    Bound::Included(end) | Bound::Excluded(end) => end,
4310                    Bound::Unbounded => region.range.end,
4311                };
4312                let end_overshoot = end_offset.saturating_sub(region.range.start);
4313                let start = region
4314                    .buffer_range
4315                    .end
4316                    .min(region.buffer_range.start + start_overshoot);
4317                let end = region
4318                    .buffer_range
4319                    .end
4320                    .min(region.buffer_range.start + end_overshoot);
4321                let context = region.excerpt.range.context.clone();
4322                if let Some(prev) = result.last_mut().filter(|(_, prev_range, excerpt_id, _)| {
4323                    *excerpt_id == region.excerpt.id && prev_range.end == start
4324                }) {
4325                    prev.1.end = end;
4326                } else {
4327                    result.push((region.buffer, start..end, region.excerpt.id, context));
4328                }
4329            }
4330            cursor.next();
4331        }
4332
4333        if let Some(excerpt) = cursor.excerpt() {
4334            let dominated_by_prev_excerpt =
4335                result.last().is_some_and(|(_, _, id, _)| *id == excerpt.id);
4336            if !dominated_by_prev_excerpt && excerpt.text_summary.len == 0 {
4337                let excerpt_position = self.len();
4338                if bounds.contains(&excerpt_position) {
4339                    let buffer_offset =
4340                        BufferOffset(excerpt.range.context.start.to_offset(&excerpt.buffer));
4341                    let context = excerpt.range.context.clone();
4342                    result.push((
4343                        &excerpt.buffer,
4344                        buffer_offset..buffer_offset,
4345                        excerpt.id,
4346                        context,
4347                    ));
4348                }
4349            }
4350        }
4351
4352        result
4353    }
4354
4355    pub fn range_to_buffer_ranges_with_deleted_hunks<T: ToOffset>(
4356        &self,
4357        range: Range<T>,
4358    ) -> impl Iterator<
4359        Item = (
4360            &BufferSnapshot,
4361            Range<BufferOffset>,
4362            ExcerptId,
4363            Option<Anchor>,
4364        ),
4365    > + '_ {
4366        let start = range.start.to_offset(self);
4367        let end = range.end.to_offset(self);
4368
4369        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
4370        cursor.seek(&start);
4371
4372        std::iter::from_fn(move || {
4373            let region = cursor.region()?;
4374            if region.range.start > end {
4375                return None;
4376            }
4377            let start_overshoot = start.saturating_sub(region.range.start);
4378            let end_overshoot = end.saturating_sub(region.range.start);
4379            let start = region
4380                .buffer_range
4381                .end
4382                .min(region.buffer_range.start + start_overshoot);
4383            let end = region
4384                .buffer_range
4385                .end
4386                .min(region.buffer_range.start + end_overshoot);
4387
4388            let region_excerpt_id = region.excerpt.id;
4389            let deleted_hunk_anchor = if region.is_main_buffer {
4390                None
4391            } else {
4392                Some(self.anchor_before(region.range.start))
4393            };
4394            let result = (
4395                region.buffer,
4396                start..end,
4397                region_excerpt_id,
4398                deleted_hunk_anchor,
4399            );
4400            cursor.next();
4401            Some(result)
4402        })
4403    }
4404
4405    /// Retrieves buffer metadata for the given range, and converts it into multi-buffer
4406    /// coordinates.
4407    ///
4408    /// The given callback will be called for every excerpt intersecting the given range. It will
4409    /// be passed the excerpt's buffer and the buffer range that the input range intersects.
4410    /// The callback should return an iterator of metadata items from that buffer, each paired
4411    /// with a buffer range.
4412    ///
4413    /// The returned iterator yields each of these metadata items, paired with its range in
4414    /// multi-buffer coordinates.
4415    fn lift_buffer_metadata<'a, MBD, M, I>(
4416        &'a self,
4417        query_range: Range<MBD>,
4418        get_buffer_metadata: impl 'a + Fn(&'a BufferSnapshot, Range<MBD::TextDimension>) -> Option<I>,
4419    ) -> impl Iterator<Item = (Range<MBD>, M, &'a Excerpt)> + 'a
4420    where
4421        I: Iterator<Item = (Range<MBD::TextDimension>, M)> + 'a,
4422        MBD: MultiBufferDimension
4423            + Ord
4424            + Sub<Output = MBD::TextDimension>
4425            + ops::Add<MBD::TextDimension, Output = MBD>
4426            + ops::AddAssign<MBD::TextDimension>,
4427        MBD::TextDimension: Sub<Output = MBD::TextDimension>
4428            + ops::Add<Output = MBD::TextDimension>
4429            + AddAssign<MBD::TextDimension>
4430            + Ord,
4431    {
4432        let mut current_excerpt_metadata: Option<(ExcerptId, I)> = None;
4433        let mut cursor = self.cursor::<MBD, MBD::TextDimension>();
4434
4435        // Find the excerpt and buffer offset where the given range ends.
4436        cursor.seek(&query_range.end);
4437        let mut range_end = None;
4438        while let Some(region) = cursor.region() {
4439            if region.is_main_buffer {
4440                let mut buffer_end = region.buffer_range.start;
4441                let overshoot = if query_range.end > region.range.start {
4442                    query_range.end - region.range.start
4443                } else {
4444                    <MBD::TextDimension>::default()
4445                };
4446                buffer_end = buffer_end + overshoot;
4447                range_end = Some((region.excerpt.id, buffer_end));
4448                break;
4449            }
4450            cursor.next();
4451        }
4452
4453        cursor.seek(&query_range.start);
4454
4455        if let Some(region) = cursor.region().filter(|region| !region.is_main_buffer)
4456            && region.range.start > MBD::default()
4457        {
4458            cursor.prev()
4459        } else if let Some(region) = cursor.region()
4460            && region.is_main_buffer
4461            && region.diff_hunk_status.is_some()
4462        {
4463            cursor.prev();
4464            if cursor.region().is_none_or(|region| region.is_main_buffer) {
4465                cursor.next();
4466            }
4467        }
4468
4469        iter::from_fn(move || {
4470            loop {
4471                let excerpt = cursor.excerpt()?;
4472
4473                // If we have already retrieved metadata for this excerpt, continue to use it.
4474                let metadata_iter = if let Some((_, metadata)) = current_excerpt_metadata
4475                    .as_mut()
4476                    .filter(|(excerpt_id, _)| *excerpt_id == excerpt.id)
4477                {
4478                    Some(metadata)
4479                }
4480                // Otherwise, compute the intersection of the input range with the excerpt's range,
4481                // and retrieve the metadata for the resulting range.
4482                else {
4483                    let region = cursor.region()?;
4484                    let mut buffer_start;
4485                    if region.is_main_buffer {
4486                        buffer_start = region.buffer_range.start;
4487                        if query_range.start > region.range.start {
4488                            let overshoot = query_range.start - region.range.start;
4489                            buffer_start = buffer_start + overshoot;
4490                        }
4491                        buffer_start = buffer_start.min(region.buffer_range.end);
4492                    } else {
4493                        buffer_start = cursor.main_buffer_position()?;
4494                    };
4495                    let mut buffer_end = excerpt
4496                        .range
4497                        .context
4498                        .end
4499                        .summary::<MBD::TextDimension>(&excerpt.buffer);
4500                    if let Some((end_excerpt_id, end_buffer_offset)) = range_end
4501                        && excerpt.id == end_excerpt_id
4502                    {
4503                        buffer_end = buffer_end.min(end_buffer_offset);
4504                    }
4505
4506                    get_buffer_metadata(&excerpt.buffer, buffer_start..buffer_end).map(|iterator| {
4507                        &mut current_excerpt_metadata.insert((excerpt.id, iterator)).1
4508                    })
4509                };
4510
4511                // Visit each metadata item.
4512                if let Some((metadata_buffer_range, metadata)) =
4513                    metadata_iter.and_then(Iterator::next)
4514                {
4515                    // Find the multibuffer regions that contain the start and end of
4516                    // the metadata item's range.
4517                    if metadata_buffer_range.start > <MBD::TextDimension>::default() {
4518                        while let Some(region) = cursor.region() {
4519                            if (region.is_main_buffer
4520                                && (region.buffer_range.end >= metadata_buffer_range.start
4521                                    || cursor.is_at_end_of_excerpt()))
4522                                || (!region.is_main_buffer
4523                                    && region.buffer_range.start == metadata_buffer_range.start)
4524                            {
4525                                break;
4526                            }
4527                            cursor.next();
4528                        }
4529                    }
4530                    let start_region = cursor.region()?.clone();
4531                    while let Some(region) = cursor.region() {
4532                        if region.is_main_buffer
4533                            && (region.buffer_range.end > metadata_buffer_range.end
4534                                || cursor.is_at_end_of_excerpt())
4535                        {
4536                            break;
4537                        }
4538                        cursor.next();
4539                    }
4540                    let end_region = cursor.region();
4541
4542                    // Convert the metadata item's range into multibuffer coordinates.
4543                    let mut start_position = start_region.range.start;
4544                    let region_buffer_start = start_region.buffer_range.start;
4545                    if start_region.is_main_buffer
4546                        && metadata_buffer_range.start > region_buffer_start
4547                    {
4548                        start_position =
4549                            start_position + (metadata_buffer_range.start - region_buffer_start);
4550                        start_position = start_position.min(start_region.range.end);
4551                    }
4552
4553                    let mut end_position = self.max_position();
4554                    if let Some(end_region) = &end_region {
4555                        end_position = end_region.range.start;
4556                        debug_assert!(end_region.is_main_buffer);
4557                        let region_buffer_start = end_region.buffer_range.start;
4558                        if metadata_buffer_range.end > region_buffer_start {
4559                            end_position =
4560                                end_position + (metadata_buffer_range.end - region_buffer_start);
4561                        }
4562                        end_position = end_position.min(end_region.range.end);
4563                    }
4564
4565                    if start_position <= query_range.end && end_position >= query_range.start {
4566                        return Some((start_position..end_position, metadata, excerpt));
4567                    }
4568                }
4569                // When there are no more metadata items for this excerpt, move to the next excerpt.
4570                else {
4571                    current_excerpt_metadata.take();
4572                    if let Some((end_excerpt_id, _)) = range_end
4573                        && excerpt.id == end_excerpt_id
4574                    {
4575                        return None;
4576                    }
4577                    cursor.next_excerpt_forwards();
4578                }
4579            }
4580        })
4581    }
4582
4583    pub fn diff_hunk_before<T: ToOffset>(&self, position: T) -> Option<MultiBufferRow> {
4584        let offset = position.to_offset(self);
4585
4586        let mut cursor = self
4587            .cursor::<DimensionPair<MultiBufferOffset, Point>, DimensionPair<BufferOffset, Point>>(
4588            );
4589        cursor.seek(&DimensionPair {
4590            key: offset,
4591            value: None,
4592        });
4593        cursor.seek_to_start_of_current_excerpt();
4594        let excerpt = cursor.excerpt()?;
4595
4596        let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
4597        let excerpt_end = excerpt.range.context.end.to_offset(&excerpt.buffer);
4598        let current_position = self
4599            .anchor_before(offset)
4600            .text_anchor
4601            .to_offset(&excerpt.buffer);
4602
4603        if let Some(diff) = self.diffs.get(&excerpt.buffer_id) {
4604            if let Some(main_buffer) = &diff.main_buffer {
4605                for hunk in diff
4606                    .hunks_intersecting_base_text_range_rev(excerpt_start..excerpt_end, main_buffer)
4607                {
4608                    if hunk.diff_base_byte_range.end >= current_position {
4609                        continue;
4610                    }
4611                    let hunk_start = excerpt.buffer.anchor_after(hunk.diff_base_byte_range.start);
4612                    let start = Anchor::in_buffer(excerpt.id, hunk_start).to_point(self);
4613                    return Some(MultiBufferRow(start.row));
4614                }
4615            } else {
4616                let excerpt_end = excerpt
4617                    .buffer
4618                    .anchor_before(excerpt_end.min(current_position));
4619                for hunk in diff.hunks_intersecting_range_rev(
4620                    excerpt.range.context.start..excerpt_end,
4621                    &excerpt.buffer,
4622                ) {
4623                    let hunk_end = hunk.buffer_range.end.to_offset(&excerpt.buffer);
4624                    if hunk_end >= current_position {
4625                        continue;
4626                    }
4627                    let start =
4628                        Anchor::in_buffer(excerpt.id, hunk.buffer_range.start).to_point(self);
4629                    return Some(MultiBufferRow(start.row));
4630                }
4631            }
4632        }
4633
4634        loop {
4635            cursor.prev_excerpt();
4636            let excerpt = cursor.excerpt()?;
4637
4638            let Some(diff) = self.diffs.get(&excerpt.buffer_id) else {
4639                continue;
4640            };
4641            if let Some(main_buffer) = &diff.main_buffer {
4642                let Some(hunk) = diff
4643                    .hunks_intersecting_base_text_range_rev(
4644                        excerpt.range.context.to_offset(&excerpt.buffer),
4645                        main_buffer,
4646                    )
4647                    .next()
4648                else {
4649                    continue;
4650                };
4651                let hunk_start = excerpt.buffer.anchor_after(hunk.diff_base_byte_range.start);
4652                let start = Anchor::in_buffer(excerpt.id, hunk_start).to_point(self);
4653                return Some(MultiBufferRow(start.row));
4654            } else {
4655                let Some(hunk) = diff
4656                    .hunks_intersecting_range_rev(excerpt.range.context.clone(), &excerpt.buffer)
4657                    .next()
4658                else {
4659                    continue;
4660                };
4661                let start = Anchor::in_buffer(excerpt.id, hunk.buffer_range.start).to_point(self);
4662                return Some(MultiBufferRow(start.row));
4663            }
4664        }
4665    }
4666
4667    pub fn has_diff_hunks(&self) -> bool {
4668        self.diffs.values().any(|diff| !diff.is_empty())
4669    }
4670
4671    pub fn is_inside_word<T: ToOffset>(
4672        &self,
4673        position: T,
4674        scope_context: Option<CharScopeContext>,
4675    ) -> bool {
4676        let position = position.to_offset(self);
4677        let classifier = self
4678            .char_classifier_at(position)
4679            .scope_context(scope_context);
4680        let next_char_kind = self.chars_at(position).next().map(|c| classifier.kind(c));
4681        let prev_char_kind = self
4682            .reversed_chars_at(position)
4683            .next()
4684            .map(|c| classifier.kind(c));
4685        prev_char_kind.zip(next_char_kind) == Some((CharKind::Word, CharKind::Word))
4686    }
4687
4688    pub fn surrounding_word<T: ToOffset>(
4689        &self,
4690        start: T,
4691        scope_context: Option<CharScopeContext>,
4692    ) -> (Range<MultiBufferOffset>, Option<CharKind>) {
4693        let mut start = start.to_offset(self);
4694        let mut end = start;
4695        let mut next_chars = self.chars_at(start).peekable();
4696        let mut prev_chars = self.reversed_chars_at(start).peekable();
4697
4698        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4699
4700        let word_kind = cmp::max(
4701            prev_chars.peek().copied().map(|c| classifier.kind(c)),
4702            next_chars.peek().copied().map(|c| classifier.kind(c)),
4703        );
4704
4705        for ch in prev_chars {
4706            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4707                start -= ch.len_utf8();
4708            } else {
4709                break;
4710            }
4711        }
4712
4713        for ch in next_chars {
4714            if Some(classifier.kind(ch)) == word_kind && ch != '\n' {
4715                end += ch.len_utf8();
4716            } else {
4717                break;
4718            }
4719        }
4720
4721        (start..end, word_kind)
4722    }
4723
4724    pub fn char_kind_before<T: ToOffset>(
4725        &self,
4726        start: T,
4727        scope_context: Option<CharScopeContext>,
4728    ) -> Option<CharKind> {
4729        let start = start.to_offset(self);
4730        let classifier = self.char_classifier_at(start).scope_context(scope_context);
4731        self.reversed_chars_at(start)
4732            .next()
4733            .map(|ch| classifier.kind(ch))
4734    }
4735
4736    pub fn is_singleton(&self) -> bool {
4737        self.singleton
4738    }
4739
4740    pub fn as_singleton(&self) -> Option<(ExcerptId, BufferId, &BufferSnapshot)> {
4741        if self.singleton {
4742            self.excerpts
4743                .iter()
4744                .next()
4745                .map(|e| (e.id, e.buffer_id, &*e.buffer))
4746        } else {
4747            None
4748        }
4749    }
4750
4751    pub fn len(&self) -> MultiBufferOffset {
4752        self.diff_transforms.summary().output.len
4753    }
4754
4755    pub fn max_position<MBD: MultiBufferDimension>(&self) -> MBD {
4756        MBD::from_summary(&self.text_summary())
4757    }
4758
4759    pub fn is_empty(&self) -> bool {
4760        self.diff_transforms.summary().output.len == MultiBufferOffset(0)
4761    }
4762
4763    pub fn widest_line_number(&self) -> u32 {
4764        // widest_line_number is 0-based, so 1 is added to get the displayed line number.
4765        self.excerpts.summary().widest_line_number + 1
4766    }
4767
4768    pub fn bytes_in_range<T: ToOffset>(&self, range: Range<T>) -> MultiBufferBytes<'_> {
4769        let range = range.start.to_offset(self)..range.end.to_offset(self);
4770        let mut excerpts = self.cursor::<MultiBufferOffset, BufferOffset>();
4771        excerpts.seek(&range.start);
4772
4773        let mut chunk;
4774        let mut has_trailing_newline;
4775        let excerpt_bytes;
4776        if let Some(region) = excerpts.region() {
4777            let mut bytes = region.buffer.bytes_in_range(
4778                region.buffer_range.start + (range.start - region.range.start)
4779                    ..(region.buffer_range.start + (range.end - region.range.start))
4780                        .min(region.buffer_range.end),
4781            );
4782            chunk = bytes.next().unwrap_or(&[][..]);
4783            excerpt_bytes = Some(bytes);
4784            has_trailing_newline = region.has_trailing_newline && range.end >= region.range.end;
4785            if chunk.is_empty() && has_trailing_newline {
4786                chunk = b"\n";
4787                has_trailing_newline = false;
4788            }
4789        } else {
4790            chunk = &[][..];
4791            excerpt_bytes = None;
4792            has_trailing_newline = false;
4793        };
4794
4795        MultiBufferBytes {
4796            range,
4797            cursor: excerpts,
4798            excerpt_bytes,
4799            has_trailing_newline,
4800            chunk,
4801        }
4802    }
4803
4804    pub fn reversed_bytes_in_range<T: ToOffset>(
4805        &self,
4806        range: Range<T>,
4807    ) -> ReversedMultiBufferBytes<'_> {
4808        let range = range.start.to_offset(self)..range.end.to_offset(self);
4809        let mut chunks = self.reversed_chunks_in_range(range.clone());
4810        let chunk = chunks.next().map_or(&[][..], |c| c.as_bytes());
4811        ReversedMultiBufferBytes {
4812            range,
4813            chunks,
4814            chunk,
4815        }
4816    }
4817
4818    pub fn row_infos(&self, start_row: MultiBufferRow) -> MultiBufferRows<'_> {
4819        let mut cursor = self.cursor::<Point, Point>();
4820        cursor.seek(&Point::new(start_row.0, 0));
4821        let mut result = MultiBufferRows {
4822            point: Point::new(0, 0),
4823            is_empty: self.excerpts.is_empty(),
4824            is_singleton: self.is_singleton(),
4825            cursor,
4826        };
4827        result.seek(start_row);
4828        result
4829    }
4830
4831    pub fn chunks<T: ToOffset>(
4832        &self,
4833        range: Range<T>,
4834        language_aware: bool,
4835    ) -> MultiBufferChunks<'_> {
4836        let mut chunks = MultiBufferChunks {
4837            excerpt_offset_range: ExcerptDimension(MultiBufferOffset::ZERO)
4838                ..ExcerptDimension(MultiBufferOffset::ZERO),
4839            range: MultiBufferOffset::ZERO..MultiBufferOffset::ZERO,
4840            excerpts: self.excerpts.cursor(()),
4841            diff_transforms: self.diff_transforms.cursor(()),
4842            diffs: &self.diffs,
4843            diff_base_chunks: None,
4844            excerpt_chunks: None,
4845            buffer_chunk: None,
4846            language_aware,
4847        };
4848        let range = range.start.to_offset(self)..range.end.to_offset(self);
4849        chunks.seek(range);
4850        chunks
4851    }
4852
4853    pub fn clip_offset(&self, offset: MultiBufferOffset, bias: Bias) -> MultiBufferOffset {
4854        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset)
4855    }
4856
4857    pub fn clip_point(&self, point: Point, bias: Bias) -> Point {
4858        self.clip_dimension(point, bias, text::BufferSnapshot::clip_point)
4859    }
4860
4861    pub fn clip_offset_utf16(
4862        &self,
4863        offset: MultiBufferOffsetUtf16,
4864        bias: Bias,
4865    ) -> MultiBufferOffsetUtf16 {
4866        self.clip_dimension(offset, bias, text::BufferSnapshot::clip_offset_utf16)
4867    }
4868
4869    pub fn clip_point_utf16(&self, point: Unclipped<PointUtf16>, bias: Bias) -> PointUtf16 {
4870        self.clip_dimension(point.0, bias, |buffer, point, bias| {
4871            buffer.clip_point_utf16(Unclipped(point), bias)
4872        })
4873    }
4874
4875    pub fn offset_to_point(&self, offset: MultiBufferOffset) -> Point {
4876        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point)
4877    }
4878
4879    pub fn offset_to_point_utf16(&self, offset: MultiBufferOffset) -> PointUtf16 {
4880        self.convert_dimension(offset, text::BufferSnapshot::offset_to_point_utf16)
4881    }
4882
4883    pub fn point_to_point_utf16(&self, point: Point) -> PointUtf16 {
4884        self.convert_dimension(point, text::BufferSnapshot::point_to_point_utf16)
4885    }
4886
4887    pub fn point_utf16_to_point(&self, point: PointUtf16) -> Point {
4888        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_point)
4889    }
4890
4891    #[instrument(skip_all)]
4892    pub fn point_to_offset(&self, point: Point) -> MultiBufferOffset {
4893        self.convert_dimension(point, text::BufferSnapshot::point_to_offset)
4894    }
4895
4896    pub fn point_to_offset_utf16(&self, point: Point) -> MultiBufferOffsetUtf16 {
4897        self.convert_dimension(point, text::BufferSnapshot::point_to_offset_utf16)
4898    }
4899
4900    pub fn offset_utf16_to_offset(&self, offset: MultiBufferOffsetUtf16) -> MultiBufferOffset {
4901        self.convert_dimension(offset, text::BufferSnapshot::offset_utf16_to_offset)
4902    }
4903
4904    pub fn offset_to_offset_utf16(&self, offset: MultiBufferOffset) -> MultiBufferOffsetUtf16 {
4905        self.convert_dimension(offset, text::BufferSnapshot::offset_to_offset_utf16)
4906    }
4907
4908    pub fn point_utf16_to_offset(&self, point: PointUtf16) -> MultiBufferOffset {
4909        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset)
4910    }
4911
4912    pub fn point_utf16_to_offset_utf16(&self, point: PointUtf16) -> MultiBufferOffsetUtf16 {
4913        self.convert_dimension(point, text::BufferSnapshot::point_utf16_to_offset_utf16)
4914    }
4915
4916    fn clip_dimension<MBD, BD>(
4917        &self,
4918        position: MBD,
4919        bias: Bias,
4920        clip_buffer_position: fn(&text::BufferSnapshot, BD, Bias) -> BD,
4921    ) -> MBD
4922    where
4923        MBD: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBD as Sub>::Output>,
4924        BD: TextDimension + Sub<Output = <MBD as Sub>::Output> + AddAssign<<MBD as Sub>::Output>,
4925    {
4926        let mut cursor = self.cursor::<MBD, BD>();
4927        cursor.seek(&position);
4928        if let Some(region) = cursor.region() {
4929            if position >= region.range.end {
4930                return region.range.end;
4931            }
4932            let overshoot = position - region.range.start;
4933            let mut buffer_position = region.buffer_range.start;
4934            buffer_position += overshoot;
4935            let clipped_buffer_position =
4936                clip_buffer_position(region.buffer, buffer_position, bias);
4937            let mut position = region.range.start;
4938            position += clipped_buffer_position - region.buffer_range.start;
4939            position
4940        } else {
4941            self.max_position()
4942        }
4943    }
4944
4945    #[instrument(skip_all)]
4946    fn convert_dimension<MBR1, MBR2, BR1, BR2>(
4947        &self,
4948        key: MBR1,
4949        convert_buffer_dimension: fn(&text::BufferSnapshot, BR1) -> BR2,
4950    ) -> MBR2
4951    where
4952        MBR1: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBR1 as Sub>::Output>,
4953        BR1: TextDimension + Sub<Output = <MBR1 as Sub>::Output> + AddAssign<<MBR1 as Sub>::Output>,
4954        MBR2: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBR2 as Sub>::Output>,
4955        BR2: TextDimension + Sub<Output = <MBR2 as Sub>::Output> + AddAssign<<MBR2 as Sub>::Output>,
4956    {
4957        let mut cursor = self.cursor::<DimensionPair<MBR1, MBR2>, DimensionPair<BR1, BR2>>();
4958        cursor.seek(&DimensionPair { key, value: None });
4959        if let Some(region) = cursor.region() {
4960            if key >= region.range.end.key {
4961                return region.range.end.value.unwrap();
4962            }
4963            let start_key = region.range.start.key;
4964            let start_value = region.range.start.value.unwrap();
4965            let buffer_start_key = region.buffer_range.start.key;
4966            let buffer_start_value = region.buffer_range.start.value.unwrap();
4967            let mut buffer_key = buffer_start_key;
4968            buffer_key += key - start_key;
4969            let buffer_value = convert_buffer_dimension(region.buffer, buffer_key);
4970            let mut result = start_value;
4971            result += buffer_value - buffer_start_value;
4972            result
4973        } else {
4974            self.max_position()
4975        }
4976    }
4977
4978    pub fn point_to_buffer_offset<T: ToOffset>(
4979        &self,
4980        point: T,
4981    ) -> Option<(&BufferSnapshot, BufferOffset)> {
4982        let offset = point.to_offset(self);
4983        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
4984        cursor.seek(&offset);
4985        let region = cursor.region()?;
4986        let overshoot = offset - region.range.start;
4987        let buffer_offset = region.buffer_range.start + overshoot;
4988        if buffer_offset == BufferOffset(region.buffer.len() + 1)
4989            && region.has_trailing_newline
4990            && !region.is_main_buffer
4991        {
4992            let main_buffer_position = cursor.main_buffer_position()?;
4993            let buffer_snapshot = &cursor.excerpt()?.buffer;
4994            return Some((buffer_snapshot, main_buffer_position));
4995        } else if buffer_offset > BufferOffset(region.buffer.len()) {
4996            return None;
4997        }
4998        Some((region.buffer, buffer_offset))
4999    }
5000
5001    pub fn point_to_buffer_point(
5002        &self,
5003        point: Point,
5004    ) -> Option<(&BufferSnapshot, Point, ExcerptId)> {
5005        let mut cursor = self.cursor::<Point, Point>();
5006        cursor.seek(&point);
5007        let region = cursor.region()?;
5008        let overshoot = point - region.range.start;
5009        let buffer_point = region.buffer_range.start + overshoot;
5010        let excerpt = cursor.excerpt()?;
5011        if buffer_point == region.buffer.max_point() + Point::new(1, 0)
5012            && region.has_trailing_newline
5013            && !region.is_main_buffer
5014        {
5015            return Some((&excerpt.buffer, cursor.main_buffer_position()?, excerpt.id));
5016        } else if buffer_point > region.buffer.max_point() {
5017            return None;
5018        }
5019        Some((region.buffer, buffer_point, excerpt.id))
5020    }
5021
5022    pub fn suggested_indents(
5023        &self,
5024        rows: impl IntoIterator<Item = u32>,
5025        cx: &App,
5026    ) -> BTreeMap<MultiBufferRow, IndentSize> {
5027        let mut result = BTreeMap::new();
5028        self.suggested_indents_callback(
5029            rows,
5030            &mut |row, indent| {
5031                result.insert(row, indent);
5032                ControlFlow::Continue(())
5033            },
5034            cx,
5035        );
5036        result
5037    }
5038
5039    // move this to be a generator once those are a thing
5040    pub fn suggested_indents_callback(
5041        &self,
5042        rows: impl IntoIterator<Item = u32>,
5043        cb: &mut dyn FnMut(MultiBufferRow, IndentSize) -> ControlFlow<()>,
5044        cx: &App,
5045    ) {
5046        let mut rows_for_excerpt = Vec::new();
5047        let mut cursor = self.cursor::<Point, Point>();
5048        let mut rows = rows.into_iter().peekable();
5049        let mut prev_row = u32::MAX;
5050        let mut prev_language_indent_size = IndentSize::default();
5051
5052        while let Some(row) = rows.next() {
5053            cursor.seek(&Point::new(row, 0));
5054            let Some(region) = cursor.region() else {
5055                continue;
5056            };
5057
5058            // Retrieve the language and indent size once for each disjoint region being indented.
5059            let single_indent_size = if row.saturating_sub(1) == prev_row {
5060                prev_language_indent_size
5061            } else {
5062                region
5063                    .buffer
5064                    .language_indent_size_at(Point::new(row, 0), cx)
5065            };
5066            prev_language_indent_size = single_indent_size;
5067            prev_row = row;
5068
5069            let start_buffer_row = region.buffer_range.start.row;
5070            let start_multibuffer_row = region.range.start.row;
5071            let end_multibuffer_row = region.range.end.row;
5072
5073            rows_for_excerpt.push(row);
5074            while let Some(next_row) = rows.peek().copied() {
5075                if end_multibuffer_row > next_row {
5076                    rows_for_excerpt.push(next_row);
5077                    rows.next();
5078                } else {
5079                    break;
5080                }
5081            }
5082
5083            let buffer_rows = rows_for_excerpt
5084                .drain(..)
5085                .map(|row| start_buffer_row + row - start_multibuffer_row);
5086            let buffer_indents = region
5087                .buffer
5088                .suggested_indents(buffer_rows, single_indent_size);
5089            for (row, indent) in buffer_indents {
5090                if cb(
5091                    MultiBufferRow(start_multibuffer_row + row - start_buffer_row),
5092                    indent,
5093                )
5094                .is_break()
5095                {
5096                    return;
5097                }
5098            }
5099        }
5100    }
5101
5102    pub fn indent_size_for_line(&self, row: MultiBufferRow) -> IndentSize {
5103        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
5104            let mut size = buffer.indent_size_for_line(range.start.row);
5105            size.len = size
5106                .len
5107                .min(range.end.column)
5108                .saturating_sub(range.start.column);
5109            size
5110        } else {
5111            IndentSize::spaces(0)
5112        }
5113    }
5114
5115    pub fn line_indent_for_row(&self, row: MultiBufferRow) -> LineIndent {
5116        if let Some((buffer, range)) = self.buffer_line_for_row(row) {
5117            LineIndent::from_iter(buffer.text_for_range(range).flat_map(|s| s.chars()))
5118        } else {
5119            LineIndent::spaces(0)
5120        }
5121    }
5122
5123    pub fn indent_and_comment_for_line(&self, row: MultiBufferRow, cx: &App) -> String {
5124        let mut indent = self.indent_size_for_line(row).chars().collect::<String>();
5125
5126        if self.language_settings(cx).extend_comment_on_newline
5127            && let Some(language_scope) = self.language_scope_at(Point::new(row.0, 0))
5128        {
5129            let delimiters = language_scope.line_comment_prefixes();
5130            for delimiter in delimiters {
5131                if *self
5132                    .chars_at(Point::new(row.0, indent.len() as u32))
5133                    .take(delimiter.chars().count())
5134                    .collect::<String>()
5135                    .as_str()
5136                    == **delimiter
5137                {
5138                    indent.push_str(delimiter);
5139                    break;
5140                }
5141            }
5142        }
5143
5144        indent
5145    }
5146
5147    pub fn is_line_whitespace_upto<T>(&self, position: T) -> bool
5148    where
5149        T: ToOffset,
5150    {
5151        for char in self.reversed_chars_at(position) {
5152            if !char.is_whitespace() {
5153                return false;
5154            }
5155            if char == '\n' {
5156                return true;
5157            }
5158        }
5159        true
5160    }
5161
5162    pub fn prev_non_blank_row(&self, mut row: MultiBufferRow) -> Option<MultiBufferRow> {
5163        while row.0 > 0 {
5164            row.0 -= 1;
5165            if !self.is_line_blank(row) {
5166                return Some(row);
5167            }
5168        }
5169        None
5170    }
5171
5172    pub fn line_len(&self, row: MultiBufferRow) -> u32 {
5173        if let Some((_, range)) = self.buffer_line_for_row(row) {
5174            range.end.column - range.start.column
5175        } else {
5176            0
5177        }
5178    }
5179
5180    pub fn buffer_line_for_row(
5181        &self,
5182        row: MultiBufferRow,
5183    ) -> Option<(&BufferSnapshot, Range<Point>)> {
5184        let mut cursor = self.cursor::<Point, Point>();
5185        let point = Point::new(row.0, 0);
5186        cursor.seek(&point);
5187        let region = cursor.region()?;
5188        let overshoot = point.min(region.range.end) - region.range.start;
5189        let buffer_point = region.buffer_range.start + overshoot;
5190        if buffer_point.row > region.buffer_range.end.row {
5191            return None;
5192        }
5193        let line_start = Point::new(buffer_point.row, 0).max(region.buffer_range.start);
5194        let line_end = Point::new(buffer_point.row, region.buffer.line_len(buffer_point.row))
5195            .min(region.buffer_range.end);
5196        Some((region.buffer, line_start..line_end))
5197    }
5198
5199    pub fn max_point(&self) -> Point {
5200        self.text_summary().lines
5201    }
5202
5203    pub fn max_row(&self) -> MultiBufferRow {
5204        MultiBufferRow(self.text_summary().lines.row)
5205    }
5206
5207    pub fn text_summary(&self) -> MBTextSummary {
5208        self.diff_transforms.summary().output
5209    }
5210
5211    pub fn text_summary_for_range<MBD, O>(&self, range: Range<O>) -> MBD
5212    where
5213        MBD: MultiBufferDimension + AddAssign,
5214        O: ToOffset,
5215    {
5216        let range = range.start.to_offset(self)..range.end.to_offset(self);
5217        let mut cursor = self
5218            .diff_transforms
5219            .cursor::<Dimensions<MultiBufferOffset, ExcerptOffset>>(());
5220        cursor.seek(&range.start, Bias::Right);
5221
5222        let Some(first_transform) = cursor.item() else {
5223            return MBD::from_summary(&MBTextSummary::default());
5224        };
5225
5226        let diff_transform_start = cursor.start().0;
5227        let diff_transform_end = cursor.end().0;
5228        let diff_start = range.start;
5229        let start_overshoot = diff_start - diff_transform_start;
5230        let end_overshoot = std::cmp::min(range.end, diff_transform_end) - diff_transform_start;
5231
5232        let mut result = match first_transform {
5233            DiffTransform::BufferContent { .. } => {
5234                let excerpt_start = cursor.start().1 + start_overshoot;
5235                let excerpt_end = cursor.start().1 + end_overshoot;
5236                self.text_summary_for_excerpt_offset_range(excerpt_start..excerpt_end)
5237            }
5238            DiffTransform::DeletedHunk {
5239                buffer_id,
5240                base_text_byte_range,
5241                has_trailing_newline,
5242                ..
5243            } => {
5244                let buffer_start = base_text_byte_range.start + start_overshoot;
5245                let mut buffer_end = base_text_byte_range.start + end_overshoot;
5246                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
5247                    panic!("{:?} is in non-existent deleted hunk", range.start)
5248                };
5249
5250                let include_trailing_newline =
5251                    *has_trailing_newline && range.end >= diff_transform_end;
5252                if include_trailing_newline {
5253                    buffer_end -= 1;
5254                }
5255
5256                let mut summary = base_text
5257                    .text_summary_for_range::<MBD::TextDimension, _>(buffer_start..buffer_end);
5258
5259                if include_trailing_newline {
5260                    summary.add_assign(&<MBD::TextDimension>::from_text_summary(
5261                        &TextSummary::newline(),
5262                    ))
5263                }
5264
5265                let mut result = MBD::default();
5266                result.add_text_dim(&summary);
5267                result
5268            }
5269        };
5270        if range.end < diff_transform_end {
5271            return result;
5272        }
5273
5274        cursor.next();
5275        result.add_mb_text_summary(
5276            &cursor
5277                .summary::<_, OutputDimension<_>>(&range.end, Bias::Right)
5278                .0,
5279        );
5280
5281        let Some(last_transform) = cursor.item() else {
5282            return result;
5283        };
5284
5285        let overshoot = range.end - cursor.start().0;
5286        let suffix = match last_transform {
5287            DiffTransform::BufferContent { .. } => {
5288                let end = cursor.start().1 + overshoot;
5289                self.text_summary_for_excerpt_offset_range::<MBD>(cursor.start().1..end)
5290            }
5291            DiffTransform::DeletedHunk {
5292                base_text_byte_range,
5293                buffer_id,
5294                has_trailing_newline,
5295                ..
5296            } => {
5297                let buffer_end = base_text_byte_range.start + overshoot;
5298                let Some(base_text) = self.diffs.get(buffer_id).map(|diff| diff.base_text()) else {
5299                    panic!("{:?} is in non-existent deleted hunk", range.end)
5300                };
5301
5302                let mut suffix = base_text.text_summary_for_range::<MBD::TextDimension, _>(
5303                    base_text_byte_range.start..buffer_end,
5304                );
5305                if *has_trailing_newline && buffer_end == base_text_byte_range.end + 1 {
5306                    suffix.add_assign(&<MBD::TextDimension>::from_text_summary(
5307                        &TextSummary::from("\n"),
5308                    ))
5309                }
5310
5311                let mut result = MBD::default();
5312                result.add_text_dim(&suffix);
5313                result
5314            }
5315        };
5316
5317        result += suffix;
5318        result
5319    }
5320
5321    fn text_summary_for_excerpt_offset_range<MBD>(&self, mut range: Range<ExcerptOffset>) -> MBD
5322    where
5323        MBD: MultiBufferDimension + AddAssign,
5324    {
5325        let mut summary = MBD::default();
5326        let mut cursor = self.excerpts.cursor::<ExcerptOffset>(());
5327        cursor.seek(&range.start, Bias::Right);
5328        if let Some(excerpt) = cursor.item() {
5329            let mut end_before_newline = cursor.end();
5330            if excerpt.has_trailing_newline {
5331                end_before_newline -= 1;
5332            }
5333
5334            let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5335            let start_in_excerpt = excerpt_start + (range.start - *cursor.start());
5336            let end_in_excerpt =
5337                excerpt_start + (cmp::min(end_before_newline, range.end) - *cursor.start());
5338            summary.add_text_dim(
5339                &excerpt
5340                    .buffer
5341                    .text_summary_for_range::<MBD::TextDimension, _>(
5342                        start_in_excerpt..end_in_excerpt,
5343                    ),
5344            );
5345
5346            if range.end > end_before_newline {
5347                summary.add_mb_text_summary(&MBTextSummary::from(TextSummary::newline()));
5348            }
5349
5350            cursor.next();
5351        }
5352
5353        if range.end > *cursor.start() {
5354            summary += cursor
5355                .summary::<_, ExcerptDimension<MBD>>(&range.end, Bias::Right)
5356                .0;
5357            if let Some(excerpt) = cursor.item() {
5358                range.end = cmp::max(*cursor.start(), range.end);
5359
5360                let excerpt_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5361                let end_in_excerpt = excerpt_start + (range.end - *cursor.start());
5362                summary.add_text_dim(
5363                    &excerpt
5364                        .buffer
5365                        .text_summary_for_range::<MBD::TextDimension, _>(
5366                            excerpt_start..end_in_excerpt,
5367                        ),
5368                );
5369            }
5370        }
5371
5372        summary
5373    }
5374
5375    pub fn summary_for_anchor<MBD>(&self, anchor: &Anchor) -> MBD
5376    where
5377        MBD: MultiBufferDimension
5378            + Ord
5379            + Sub<Output = MBD::TextDimension>
5380            + Sub<MBD::TextDimension, Output = MBD>
5381            + AddAssign<MBD::TextDimension>
5382            + Add<MBD::TextDimension, Output = MBD>,
5383        MBD::TextDimension: Sub<Output = MBD::TextDimension> + Ord,
5384    {
5385        let excerpt_id = self.latest_excerpt_id(anchor.excerpt_id);
5386        let locator = self.excerpt_locator_for_id(excerpt_id);
5387        let (start, _, mut item) = self
5388            .excerpts
5389            .find::<ExcerptSummary, _>((), locator, Bias::Left);
5390        let mut start = MBD::from_summary(&start.text);
5391        if item.is_none() && excerpt_id == ExcerptId::max() {
5392            item = self.excerpts.last();
5393            if let Some(last_summary) = self.excerpts.last_summary() {
5394                start = start - <MBD::TextDimension>::from_text_summary(&last_summary.text.into());
5395            }
5396        }
5397
5398        let excerpt_start_position = ExcerptDimension(start);
5399        if self.diff_transforms.is_empty() {
5400            if let Some(excerpt) = item {
5401                if excerpt.id != excerpt_id && excerpt_id != ExcerptId::max() {
5402                    return excerpt_start_position.0;
5403                }
5404                let excerpt_buffer_start = excerpt
5405                    .range
5406                    .context
5407                    .start
5408                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5409                let excerpt_buffer_end = excerpt
5410                    .range
5411                    .context
5412                    .end
5413                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5414                let buffer_summary = anchor
5415                    .text_anchor
5416                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5417                let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5418                let mut position = excerpt_start_position;
5419                if summary > excerpt_buffer_start {
5420                    position += summary - excerpt_buffer_start;
5421                }
5422
5423                position.0
5424            } else {
5425                excerpt_start_position.0
5426            }
5427        } else {
5428            let mut diff_transforms_cursor = self
5429                .diff_transforms
5430                .cursor::<Dimensions<ExcerptDimension<MBD>, OutputDimension<MBD>>>(());
5431            diff_transforms_cursor.next();
5432
5433            if let Some(excerpt) = item {
5434                if excerpt.id != excerpt_id && excerpt_id != ExcerptId::max() {
5435                    return self.resolve_summary_for_min_or_max_anchor(
5436                        &Anchor::min(),
5437                        excerpt_start_position,
5438                        &mut diff_transforms_cursor,
5439                    );
5440                }
5441                let excerpt_buffer_start = excerpt
5442                    .range
5443                    .context
5444                    .start
5445                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5446                let excerpt_buffer_end = excerpt
5447                    .range
5448                    .context
5449                    .end
5450                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5451                let buffer_summary = anchor
5452                    .text_anchor
5453                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5454                let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5455                let mut position = excerpt_start_position;
5456                if summary > excerpt_buffer_start {
5457                    position += summary - excerpt_buffer_start;
5458                }
5459
5460                if diff_transforms_cursor.start().0 < position {
5461                    diff_transforms_cursor.seek_forward(&position, Bias::Left);
5462                }
5463                self.resolve_summary_for_anchor(
5464                    &anchor,
5465                    position,
5466                    &mut diff_transforms_cursor,
5467                    &excerpt.buffer,
5468                )
5469            } else {
5470                diff_transforms_cursor.seek_forward(&excerpt_start_position, Bias::Left);
5471                self.resolve_summary_for_min_or_max_anchor(
5472                    &Anchor::max(),
5473                    excerpt_start_position,
5474                    &mut diff_transforms_cursor,
5475                )
5476            }
5477        }
5478    }
5479
5480    /// Maps an anchor's excerpt-space position to its output-space position by
5481    /// walking the diff transforms. The cursor is shared across consecutive
5482    /// calls, so it may already be partway through the transform list.
5483    fn resolve_summary_for_anchor<MBD>(
5484        &self,
5485        anchor: &Anchor,
5486        excerpt_position: ExcerptDimension<MBD>,
5487        diff_transforms: &mut Cursor<
5488            DiffTransform,
5489            Dimensions<ExcerptDimension<MBD>, OutputDimension<MBD>>,
5490        >,
5491        excerpt_buffer: &text::BufferSnapshot,
5492    ) -> MBD
5493    where
5494        MBD: MultiBufferDimension + Ord + Sub + AddAssign<<MBD as Sub>::Output>,
5495    {
5496        loop {
5497            let transform_end_position = diff_transforms.end().0;
5498            let item = diff_transforms.item();
5499            let at_transform_end = transform_end_position == excerpt_position && item.is_some();
5500
5501            // A right-biased anchor at a transform boundary belongs to the
5502            // *next* transform, so advance past the current one.
5503            if anchor.text_anchor.bias == Bias::Right && at_transform_end {
5504                diff_transforms.next();
5505                continue;
5506            }
5507
5508            let mut position = diff_transforms.start().1;
5509            match item {
5510                Some(DiffTransform::DeletedHunk {
5511                    buffer_id,
5512                    base_text_byte_range,
5513                    hunk_info,
5514                    ..
5515                }) => {
5516                    if let Some(diff_base_anchor) = &anchor.diff_base_anchor
5517                        && let Some(base_text) =
5518                            self.diffs.get(buffer_id).map(|diff| diff.base_text())
5519                        && diff_base_anchor.is_valid(&base_text)
5520                    {
5521                        // The anchor carries a diff-base position — resolve it
5522                        // to a location inside the deleted hunk.
5523                        let base_text_offset = diff_base_anchor.to_offset(base_text);
5524                        if base_text_offset >= base_text_byte_range.start
5525                            && base_text_offset <= base_text_byte_range.end
5526                        {
5527                            let position_in_hunk = base_text
5528                                .text_summary_for_range::<MBD::TextDimension, _>(
5529                                    base_text_byte_range.start..base_text_offset,
5530                                );
5531                            position.0.add_text_dim(&position_in_hunk);
5532                        } else if at_transform_end {
5533                            // diff_base offset falls outside this hunk's range;
5534                            // advance to see if the next transform is a better fit.
5535                            diff_transforms.next();
5536                            continue;
5537                        }
5538                    } else if at_transform_end
5539                        && anchor
5540                            .text_anchor
5541                            .cmp(&hunk_info.hunk_start_anchor, excerpt_buffer)
5542                            .is_gt()
5543                    {
5544                        // The anchor has no (valid) diff-base position, so it
5545                        // belongs in the buffer content, not in the deleted
5546                        // hunk. However, after an edit deletes the text between
5547                        // the hunk boundary and this anchor, both resolve to
5548                        // the same excerpt_position—landing us here on the
5549                        // DeletedHunk left behind by the shared cursor. Use the
5550                        // CRDT ordering to detect that the anchor is strictly
5551                        // *past* the hunk boundary and skip to the following
5552                        // BufferContent.
5553                        diff_transforms.next();
5554                        continue;
5555                    }
5556                }
5557                _ => {
5558                    // On a BufferContent (or no transform). If the anchor
5559                    // carries a diff_base_anchor it needs a DeletedHunk, so
5560                    // advance to find one.
5561                    if at_transform_end && anchor.diff_base_anchor.is_some() {
5562                        diff_transforms.next();
5563                        continue;
5564                    }
5565                    let overshoot = excerpt_position - diff_transforms.start().0;
5566                    position += overshoot;
5567                }
5568            }
5569
5570            return position.0;
5571        }
5572    }
5573
5574    /// Like `resolve_summary_for_anchor` but optimized for min/max anchors.
5575    fn resolve_summary_for_min_or_max_anchor<MBD>(
5576        &self,
5577        anchor: &Anchor,
5578        excerpt_position: ExcerptDimension<MBD>,
5579        diff_transforms: &mut Cursor<
5580            DiffTransform,
5581            Dimensions<ExcerptDimension<MBD>, OutputDimension<MBD>>,
5582        >,
5583    ) -> MBD
5584    where
5585        MBD: MultiBufferDimension + Ord + Sub + AddAssign<<MBD as Sub>::Output>,
5586    {
5587        loop {
5588            let transform_end_position = diff_transforms.end().0;
5589            let item = diff_transforms.item();
5590            let at_transform_end = transform_end_position == excerpt_position && item.is_some();
5591
5592            // A right-biased anchor at a transform boundary belongs to the
5593            // *next* transform, so advance past the current one.
5594            if anchor.text_anchor.bias == Bias::Right && at_transform_end {
5595                diff_transforms.next();
5596                continue;
5597            }
5598
5599            let mut position = diff_transforms.start().1;
5600            if let Some(DiffTransform::BufferContent { .. }) | None = item {
5601                let overshoot = excerpt_position - diff_transforms.start().0;
5602                position += overshoot;
5603            }
5604
5605            return position.0;
5606        }
5607    }
5608
5609    fn excerpt_offset_for_anchor(&self, anchor: &Anchor) -> ExcerptOffset {
5610        let mut cursor = self
5611            .excerpts
5612            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
5613        let locator = self.excerpt_locator_for_id(anchor.excerpt_id);
5614
5615        cursor.seek(&Some(locator), Bias::Left);
5616        if cursor.item().is_none() && anchor.excerpt_id == ExcerptId::max() {
5617            cursor.prev();
5618        }
5619
5620        let mut position = cursor.start().1;
5621        if let Some(excerpt) = cursor.item()
5622            && (excerpt.id == anchor.excerpt_id || anchor.excerpt_id == ExcerptId::max())
5623        {
5624            let excerpt_buffer_start = excerpt
5625                .buffer
5626                .offset_for_anchor(&excerpt.range.context.start);
5627            let excerpt_buffer_end = excerpt.buffer.offset_for_anchor(&excerpt.range.context.end);
5628            let buffer_position = cmp::min(
5629                excerpt_buffer_end,
5630                excerpt.buffer.offset_for_anchor(&anchor.text_anchor),
5631            );
5632            if buffer_position > excerpt_buffer_start {
5633                position += buffer_position - excerpt_buffer_start;
5634            }
5635        }
5636        position
5637    }
5638
5639    pub fn latest_excerpt_id(&self, mut excerpt_id: ExcerptId) -> ExcerptId {
5640        while let Some(replacement) = self.replaced_excerpts.get(&excerpt_id) {
5641            excerpt_id = *replacement;
5642        }
5643        excerpt_id
5644    }
5645
5646    pub fn summaries_for_anchors<'a, MBD, I>(&'a self, anchors: I) -> Vec<MBD>
5647    where
5648        MBD: MultiBufferDimension
5649            + Ord
5650            + Sub<Output = MBD::TextDimension>
5651            + AddAssign<MBD::TextDimension>,
5652        MBD::TextDimension: Sub<Output = MBD::TextDimension> + Ord,
5653        I: 'a + IntoIterator<Item = &'a Anchor>,
5654    {
5655        let mut anchors = anchors.into_iter().peekable();
5656        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
5657        let mut diff_transforms_cursor = self
5658            .diff_transforms
5659            .cursor::<Dimensions<ExcerptDimension<MBD>, OutputDimension<MBD>>>(());
5660        diff_transforms_cursor.next();
5661
5662        let mut summaries = Vec::new();
5663        while let Some(anchor) = anchors.peek() {
5664            let excerpt_id = self.latest_excerpt_id(anchor.excerpt_id);
5665
5666            let excerpt_anchors = anchors.peeking_take_while(|anchor| {
5667                self.latest_excerpt_id(anchor.excerpt_id) == excerpt_id
5668            });
5669
5670            let locator = self.excerpt_locator_for_id(excerpt_id);
5671            cursor.seek_forward(locator, Bias::Left);
5672            if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
5673                cursor.prev();
5674            }
5675
5676            let excerpt_start_position = ExcerptDimension(MBD::from_summary(&cursor.start().text));
5677            if let Some(excerpt) = cursor.item() {
5678                if excerpt.id != excerpt_id && excerpt_id != ExcerptId::max() {
5679                    let position = self.resolve_summary_for_min_or_max_anchor(
5680                        &Anchor::min(),
5681                        excerpt_start_position,
5682                        &mut diff_transforms_cursor,
5683                    );
5684                    summaries.extend(excerpt_anchors.map(|_| position));
5685                    continue;
5686                }
5687                let excerpt_buffer_start = excerpt
5688                    .range
5689                    .context
5690                    .start
5691                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5692                let excerpt_buffer_end = excerpt
5693                    .range
5694                    .context
5695                    .end
5696                    .summary::<MBD::TextDimension>(&excerpt.buffer);
5697                for (buffer_summary, anchor) in excerpt
5698                    .buffer
5699                    .summaries_for_anchors_with_payload::<MBD::TextDimension, _, _>(
5700                        excerpt_anchors.map(|a| (&a.text_anchor, a)),
5701                    )
5702                {
5703                    let summary = cmp::min(excerpt_buffer_end, buffer_summary);
5704                    let mut position = excerpt_start_position;
5705                    if summary > excerpt_buffer_start {
5706                        position += summary - excerpt_buffer_start;
5707                    }
5708
5709                    if diff_transforms_cursor.start().0 < position {
5710                        diff_transforms_cursor.seek_forward(&position, Bias::Left);
5711                    }
5712
5713                    summaries.push(self.resolve_summary_for_anchor(
5714                        anchor,
5715                        position,
5716                        &mut diff_transforms_cursor,
5717                        &excerpt.buffer,
5718                    ));
5719                }
5720            } else {
5721                diff_transforms_cursor.seek_forward(&excerpt_start_position, Bias::Left);
5722                let position = self.resolve_summary_for_min_or_max_anchor(
5723                    &Anchor::max(),
5724                    excerpt_start_position,
5725                    &mut diff_transforms_cursor,
5726                );
5727                summaries.extend(excerpt_anchors.map(|_| position));
5728            }
5729        }
5730
5731        summaries
5732    }
5733
5734    pub fn dimensions_from_points<'a, MBD>(
5735        &'a self,
5736        points: impl 'a + IntoIterator<Item = Point>,
5737    ) -> impl 'a + Iterator<Item = MBD>
5738    where
5739        MBD: MultiBufferDimension + Sub + AddAssign<<MBD as Sub>::Output>,
5740    {
5741        let mut cursor = self.cursor::<DimensionPair<Point, MBD>, Point>();
5742        cursor.seek(&DimensionPair {
5743            key: Point::default(),
5744            value: None,
5745        });
5746        let mut points = points.into_iter();
5747        iter::from_fn(move || {
5748            let point = points.next()?;
5749
5750            cursor.seek_forward(&DimensionPair {
5751                key: point,
5752                value: None,
5753            });
5754
5755            if let Some(region) = cursor.region() {
5756                let overshoot = point - region.range.start.key;
5757                let buffer_point = region.buffer_range.start + overshoot;
5758                let mut position = region.range.start.value.unwrap();
5759                position.add_text_dim(
5760                    &region
5761                        .buffer
5762                        .text_summary_for_range(region.buffer_range.start..buffer_point),
5763                );
5764                if point == region.range.end.key && region.has_trailing_newline {
5765                    position.add_mb_text_summary(&MBTextSummary::from(TextSummary::newline()));
5766                }
5767                Some(position)
5768            } else {
5769                Some(MBD::from_summary(&self.text_summary()))
5770            }
5771        })
5772    }
5773
5774    pub fn refresh_anchors<'a, I>(&'a self, anchors: I) -> Vec<(usize, Anchor, bool)>
5775    where
5776        I: 'a + IntoIterator<Item = &'a Anchor>,
5777    {
5778        let mut anchors = anchors.into_iter().enumerate().peekable();
5779        let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
5780        cursor.next();
5781
5782        let mut result = Vec::new();
5783
5784        while let Some((_, anchor)) = anchors.peek() {
5785            let old_excerpt_id = anchor.excerpt_id;
5786
5787            // Find the location where this anchor's excerpt should be.
5788            let old_locator = self.excerpt_locator_for_id(old_excerpt_id);
5789            cursor.seek_forward(&Some(old_locator), Bias::Left);
5790
5791            let next_excerpt = cursor.item();
5792            let prev_excerpt = cursor.prev_item();
5793
5794            // Process all of the anchors for this excerpt.
5795            while let Some((anchor_ix, &anchor)) =
5796                anchors.next_if(|(_, anchor)| anchor.excerpt_id == old_excerpt_id)
5797            {
5798                let mut anchor = anchor;
5799
5800                // Leave min and max anchors unchanged if invalid or
5801                // if the old excerpt still exists at this location
5802                let mut kept_position = next_excerpt
5803                    .is_some_and(|e| e.id == old_excerpt_id && e.contains(&anchor))
5804                    || old_excerpt_id == ExcerptId::max()
5805                    || old_excerpt_id == ExcerptId::min();
5806
5807                // If the old excerpt no longer exists at this location, then attempt to
5808                // find an equivalent position for this anchor in an adjacent excerpt.
5809                if !kept_position {
5810                    for excerpt in [next_excerpt, prev_excerpt].iter().filter_map(|e| *e) {
5811                        if excerpt.contains(&anchor) {
5812                            anchor.excerpt_id = excerpt.id;
5813                            kept_position = true;
5814                            break;
5815                        }
5816                    }
5817                }
5818
5819                // If there's no adjacent excerpt that contains the anchor's position,
5820                // then report that the anchor has lost its position.
5821                if !kept_position {
5822                    anchor = if let Some(excerpt) = next_excerpt {
5823                        let mut text_anchor = excerpt
5824                            .range
5825                            .context
5826                            .start
5827                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5828                        if text_anchor
5829                            .cmp(&excerpt.range.context.end, &excerpt.buffer)
5830                            .is_gt()
5831                        {
5832                            text_anchor = excerpt.range.context.end;
5833                        }
5834                        Anchor::in_buffer(excerpt.id, text_anchor)
5835                    } else if let Some(excerpt) = prev_excerpt {
5836                        let mut text_anchor = excerpt
5837                            .range
5838                            .context
5839                            .end
5840                            .bias(anchor.text_anchor.bias, &excerpt.buffer);
5841                        if text_anchor
5842                            .cmp(&excerpt.range.context.start, &excerpt.buffer)
5843                            .is_lt()
5844                        {
5845                            text_anchor = excerpt.range.context.start;
5846                        }
5847                        Anchor::in_buffer(excerpt.id, text_anchor)
5848                    } else if anchor.text_anchor.bias == Bias::Left {
5849                        Anchor::min()
5850                    } else {
5851                        Anchor::max()
5852                    };
5853                }
5854
5855                result.push((anchor_ix, anchor, kept_position));
5856            }
5857        }
5858        result.sort_unstable_by(|a, b| a.1.cmp(&b.1, self));
5859        result
5860    }
5861
5862    pub fn anchor_before<T: ToOffset>(&self, position: T) -> Anchor {
5863        self.anchor_at(position, Bias::Left)
5864    }
5865
5866    pub fn anchor_after<T: ToOffset>(&self, position: T) -> Anchor {
5867        self.anchor_at(position, Bias::Right)
5868    }
5869
5870    pub fn anchor_at<T: ToOffset>(&self, position: T, mut bias: Bias) -> Anchor {
5871        let offset = position.to_offset(self);
5872
5873        // Find the given position in the diff transforms. Determine the corresponding
5874        // offset in the excerpts, and whether the position is within a deleted hunk.
5875        let mut diff_transforms = self
5876            .diff_transforms
5877            .cursor::<Dimensions<MultiBufferOffset, ExcerptOffset>>(());
5878        diff_transforms.seek(&offset, Bias::Right);
5879
5880        if offset == diff_transforms.start().0
5881            && bias == Bias::Left
5882            && let Some(prev_item) = diff_transforms.prev_item()
5883            && let DiffTransform::DeletedHunk { .. } = prev_item
5884        {
5885            diff_transforms.prev();
5886        }
5887        let offset_in_transform = offset - diff_transforms.start().0;
5888        let mut excerpt_offset = diff_transforms.start().1;
5889        let mut diff_base_anchor = None;
5890        if let Some(DiffTransform::DeletedHunk {
5891            buffer_id,
5892            base_text_byte_range,
5893            has_trailing_newline,
5894            ..
5895        }) = diff_transforms.item()
5896        {
5897            let diff = self.diffs.get(buffer_id).expect("missing diff");
5898            if offset_in_transform > base_text_byte_range.len() {
5899                debug_assert!(*has_trailing_newline);
5900                bias = Bias::Right;
5901            } else {
5902                diff_base_anchor = Some(
5903                    diff.base_text()
5904                        .anchor_at(base_text_byte_range.start + offset_in_transform, bias),
5905                );
5906                bias = Bias::Left;
5907            }
5908        } else {
5909            excerpt_offset += MultiBufferOffset(offset_in_transform);
5910        };
5911
5912        let mut excerpts = self
5913            .excerpts
5914            .cursor::<Dimensions<ExcerptOffset, Option<ExcerptId>>>(());
5915        excerpts.seek(&excerpt_offset, Bias::Right);
5916        if excerpts.item().is_none() && excerpt_offset == excerpts.start().0 && bias == Bias::Left {
5917            excerpts.prev();
5918        }
5919        if let Some(excerpt) = excerpts.item() {
5920            let mut overshoot = excerpt_offset.saturating_sub(excerpts.start().0);
5921            if excerpt.has_trailing_newline && excerpt_offset == excerpts.end().0 {
5922                overshoot -= 1;
5923                bias = Bias::Right;
5924            }
5925
5926            let buffer_start = excerpt.range.context.start.to_offset(&excerpt.buffer);
5927            let text_anchor =
5928                excerpt.clip_anchor(excerpt.buffer.anchor_at(buffer_start + overshoot, bias));
5929            let anchor = Anchor::in_buffer(excerpt.id, text_anchor);
5930            match diff_base_anchor {
5931                Some(diff_base_anchor) => anchor.with_diff_base_anchor(diff_base_anchor),
5932                None => anchor,
5933            }
5934        } else if excerpt_offset == ExcerptDimension(MultiBufferOffset::ZERO) && bias == Bias::Left
5935        {
5936            Anchor::min()
5937        } else {
5938            Anchor::max()
5939        }
5940    }
5941
5942    /// Wraps the [`text::Anchor`] in a [`crate::Anchor`] if this multi-buffer is a singleton.
5943    pub fn as_singleton_anchor(&self, text_anchor: text::Anchor) -> Option<Anchor> {
5944        let (excerpt, buffer, _) = self.as_singleton()?;
5945        if text_anchor.buffer_id.is_none_or(|id| id == buffer) {
5946            Some(Anchor::in_buffer(excerpt, text_anchor))
5947        } else {
5948            None
5949        }
5950    }
5951
5952    /// Returns an anchor for the given excerpt and text anchor,
5953    /// Returns [`None`] if the excerpt_id is no longer valid or the text anchor range is out of excerpt's bounds.
5954    pub fn anchor_range_in_excerpt(
5955        &self,
5956        excerpt_id: ExcerptId,
5957        text_anchor: Range<text::Anchor>,
5958    ) -> Option<Range<Anchor>> {
5959        let excerpt = self.excerpt(self.latest_excerpt_id(excerpt_id))?;
5960
5961        Some(
5962            Self::anchor_in_excerpt_(excerpt, text_anchor.start)?
5963                ..Self::anchor_in_excerpt_(excerpt, text_anchor.end)?,
5964        )
5965    }
5966
5967    /// Returns an anchor for the given excerpt and text anchor,
5968    /// Returns [`None`] if the excerpt_id is no longer valid or the text anchor range is out of excerpt's bounds.
5969    pub fn anchor_in_excerpt(
5970        &self,
5971        excerpt_id: ExcerptId,
5972        text_anchor: text::Anchor,
5973    ) -> Option<Anchor> {
5974        let excerpt = self.excerpt(self.latest_excerpt_id(excerpt_id))?;
5975        Self::anchor_in_excerpt_(excerpt, text_anchor)
5976    }
5977
5978    /// Same as [`MultiBuffer::anchor_in_excerpt`], but more efficient than calling it multiple times.
5979    pub fn anchors_in_excerpt(
5980        &self,
5981        excerpt_id: ExcerptId,
5982        text_anchors: impl IntoIterator<Item = text::Anchor>,
5983    ) -> Option<impl Iterator<Item = Option<Anchor>>> {
5984        let excerpt = self.excerpt(self.latest_excerpt_id(excerpt_id))?;
5985        Some(
5986            text_anchors
5987                .into_iter()
5988                .map(|text_anchor| Self::anchor_in_excerpt_(excerpt, text_anchor)),
5989        )
5990    }
5991
5992    fn anchor_in_excerpt_(excerpt: &Excerpt, text_anchor: text::Anchor) -> Option<Anchor> {
5993        match text_anchor.buffer_id {
5994            Some(buffer_id) if buffer_id == excerpt.buffer_id => (),
5995            Some(_) => return None,
5996            None if text_anchor.is_max() || text_anchor.is_min() => {
5997                return Some(Anchor::in_buffer(excerpt.id, text_anchor));
5998            }
5999            None => return None,
6000        }
6001
6002        let context = &excerpt.range.context;
6003        if context.start.cmp(&text_anchor, &excerpt.buffer).is_gt()
6004            || context.end.cmp(&text_anchor, &excerpt.buffer).is_lt()
6005        {
6006            return None;
6007        }
6008
6009        Some(Anchor::in_buffer(excerpt.id, text_anchor))
6010    }
6011
6012    pub fn context_range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<text::Anchor>> {
6013        Some(self.excerpt(excerpt_id)?.range.context.clone())
6014    }
6015
6016    pub fn excerpt_range_for_excerpt(
6017        &self,
6018        excerpt_id: ExcerptId,
6019    ) -> Option<ExcerptRange<text::Anchor>> {
6020        Some(self.excerpt(excerpt_id)?.range.clone())
6021    }
6022
6023    pub fn can_resolve(&self, anchor: &Anchor) -> bool {
6024        if anchor.is_min() || anchor.is_max() {
6025            // todo(lw): should be `!self.is_empty()`
6026            true
6027        } else if let Some(excerpt) = self.excerpt(anchor.excerpt_id) {
6028            excerpt.buffer.can_resolve(&anchor.text_anchor)
6029        } else {
6030            false
6031        }
6032    }
6033
6034    pub fn excerpts(
6035        &self,
6036    ) -> impl Iterator<Item = (ExcerptId, &BufferSnapshot, ExcerptRange<text::Anchor>)> {
6037        self.excerpts
6038            .iter()
6039            .map(|excerpt| (excerpt.id, &*excerpt.buffer, excerpt.range.clone()))
6040    }
6041
6042    fn cursor<'a, MBD, BD>(&'a self) -> MultiBufferCursor<'a, MBD, BD>
6043    where
6044        MBD: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBD as Sub>::Output>,
6045        BD: TextDimension + AddAssign<<MBD as Sub>::Output>,
6046    {
6047        let excerpts = self.excerpts.cursor(());
6048        let diff_transforms = self.diff_transforms.cursor(());
6049        MultiBufferCursor {
6050            excerpts,
6051            diff_transforms,
6052            diffs: &self.diffs,
6053            cached_region: OnceCell::new(),
6054        }
6055    }
6056
6057    pub fn excerpt_before(&self, excerpt_id: ExcerptId) -> Option<MultiBufferExcerpt<'_>> {
6058        let start_locator = self.excerpt_locator_for_id(excerpt_id);
6059        let mut excerpts = self
6060            .excerpts
6061            .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
6062        excerpts.seek(&Some(start_locator), Bias::Left);
6063        excerpts.prev();
6064
6065        let mut diff_transforms = self
6066            .diff_transforms
6067            .cursor::<DiffTransforms<MultiBufferOffset>>(());
6068        diff_transforms.seek(&excerpts.start().1, Bias::Left);
6069        if diff_transforms.end().excerpt_dimension < excerpts.start().1 {
6070            diff_transforms.next();
6071        }
6072
6073        let excerpt = excerpts.item()?;
6074        Some(MultiBufferExcerpt {
6075            excerpt,
6076            offset: diff_transforms.start().output_dimension.0,
6077            buffer_offset: BufferOffset(excerpt.range.context.start.to_offset(&excerpt.buffer)),
6078            excerpt_offset: excerpts.start().1,
6079            diff_transforms,
6080        })
6081    }
6082
6083    pub fn excerpt_boundaries_in_range<R, T>(
6084        &self,
6085        range: R,
6086    ) -> impl Iterator<Item = ExcerptBoundary> + '_
6087    where
6088        R: RangeBounds<T>,
6089        T: ToOffset,
6090    {
6091        let start_offset;
6092        let start = match range.start_bound() {
6093            Bound::Included(start) => {
6094                start_offset = start.to_offset(self);
6095                Bound::Included(start_offset)
6096            }
6097            Bound::Excluded(_) => {
6098                panic!("not supported")
6099            }
6100            Bound::Unbounded => {
6101                start_offset = MultiBufferOffset::ZERO;
6102                Bound::Unbounded
6103            }
6104        };
6105        let end = match range.end_bound() {
6106            Bound::Included(end) => Bound::Included(end.to_offset(self)),
6107            Bound::Excluded(end) => Bound::Excluded(end.to_offset(self)),
6108            Bound::Unbounded => Bound::Unbounded,
6109        };
6110        let bounds = (start, end);
6111        let mut cursor = self.cursor::<DimensionPair<MultiBufferOffset, Point>, BufferOffset>();
6112        cursor.seek(&DimensionPair {
6113            key: start_offset,
6114            value: None,
6115        });
6116
6117        if cursor
6118            .fetch_excerpt_with_range()
6119            .is_some_and(|(_, range)| bounds.contains(&range.start.key))
6120        {
6121            cursor.prev_excerpt();
6122        } else {
6123            cursor.seek_to_start_of_current_excerpt();
6124        }
6125        let mut prev_region = cursor
6126            .fetch_excerpt_with_range()
6127            .map(|(excerpt, _)| excerpt);
6128
6129        cursor.next_excerpt_forwards();
6130
6131        iter::from_fn(move || {
6132            loop {
6133                if self.singleton {
6134                    return None;
6135                }
6136
6137                let (next_excerpt, next_range) = cursor.fetch_excerpt_with_range()?;
6138                cursor.next_excerpt_forwards();
6139                if !bounds.contains(&next_range.start.key) {
6140                    prev_region = Some(next_excerpt);
6141                    continue;
6142                }
6143
6144                let next_region_start = next_range.start.value.unwrap();
6145                let next_region_end = if let Some((_, range)) = cursor.fetch_excerpt_with_range() {
6146                    range.start.value.unwrap()
6147                } else {
6148                    self.max_point()
6149                };
6150
6151                let prev = prev_region.as_ref().map(|region| ExcerptInfo {
6152                    id: region.id,
6153                    buffer: region.buffer.clone(),
6154                    buffer_id: region.buffer_id,
6155                    range: region.range.clone(),
6156                    end_row: MultiBufferRow(next_region_start.row),
6157                });
6158
6159                let next = ExcerptInfo {
6160                    id: next_excerpt.id,
6161                    buffer: next_excerpt.buffer.clone(),
6162                    buffer_id: next_excerpt.buffer_id,
6163                    range: next_excerpt.range.clone(),
6164                    end_row: if next_excerpt.has_trailing_newline {
6165                        MultiBufferRow(next_region_end.row - 1)
6166                    } else {
6167                        MultiBufferRow(next_region_end.row)
6168                    },
6169                };
6170
6171                let row = MultiBufferRow(next_region_start.row);
6172
6173                prev_region = Some(next_excerpt);
6174
6175                return Some(ExcerptBoundary { row, prev, next });
6176            }
6177        })
6178    }
6179
6180    pub fn edit_count(&self) -> usize {
6181        self.edit_count
6182    }
6183
6184    pub fn non_text_state_update_count(&self) -> usize {
6185        self.non_text_state_update_count
6186    }
6187
6188    /// Returns the smallest enclosing bracket ranges containing the given range or
6189    /// None if no brackets contain range or the range is not contained in a single
6190    /// excerpt
6191    ///
6192    /// Can optionally pass a range_filter to filter the ranges of brackets to consider
6193    #[ztracing::instrument(skip_all)]
6194    pub fn innermost_enclosing_bracket_ranges<T: ToOffset>(
6195        &self,
6196        range: Range<T>,
6197        range_filter: Option<
6198            &dyn Fn(&BufferSnapshot, Range<BufferOffset>, Range<BufferOffset>) -> bool,
6199        >,
6200    ) -> Option<(Range<MultiBufferOffset>, Range<MultiBufferOffset>)> {
6201        let range = range.start.to_offset(self)..range.end.to_offset(self);
6202        let mut excerpt = self.excerpt_containing(range.clone())?;
6203        let buffer = excerpt.buffer();
6204        let excerpt_buffer_range = excerpt.buffer_range();
6205
6206        // Filter to ranges contained in the excerpt
6207        let range_filter = |open: Range<usize>, close: Range<usize>| -> bool {
6208            excerpt_buffer_range.contains(&BufferOffset(open.start))
6209                && excerpt_buffer_range.contains(&BufferOffset(close.end))
6210                && range_filter.is_none_or(|filter| {
6211                    filter(
6212                        buffer,
6213                        BufferOffset(open.start)..BufferOffset(close.end),
6214                        BufferOffset(close.start)..BufferOffset(close.end),
6215                    )
6216                })
6217        };
6218
6219        let (open, close) = excerpt.buffer().innermost_enclosing_bracket_ranges(
6220            excerpt.map_range_to_buffer(range),
6221            Some(&range_filter),
6222        )?;
6223
6224        Some((
6225            excerpt.map_range_from_buffer(BufferOffset(open.start)..BufferOffset(open.end)),
6226            excerpt.map_range_from_buffer(BufferOffset(close.start)..BufferOffset(close.end)),
6227        ))
6228    }
6229
6230    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
6231    /// not contained in a single excerpt
6232    pub fn enclosing_bracket_ranges<T: ToOffset>(
6233        &self,
6234        range: Range<T>,
6235    ) -> Option<impl Iterator<Item = (Range<MultiBufferOffset>, Range<MultiBufferOffset>)> + '_>
6236    {
6237        let range = range.start.to_offset(self)..range.end.to_offset(self);
6238        let mut excerpt = self.excerpt_containing(range.clone())?;
6239
6240        Some(
6241            excerpt
6242                .buffer()
6243                .enclosing_bracket_ranges(excerpt.map_range_to_buffer(range))
6244                .filter_map(move |pair| {
6245                    let open_range =
6246                        BufferOffset(pair.open_range.start)..BufferOffset(pair.open_range.end);
6247                    let close_range =
6248                        BufferOffset(pair.close_range.start)..BufferOffset(pair.close_range.end);
6249                    if excerpt.contains_buffer_range(open_range.start..close_range.end) {
6250                        Some((
6251                            excerpt.map_range_from_buffer(open_range),
6252                            excerpt.map_range_from_buffer(close_range),
6253                        ))
6254                    } else {
6255                        None
6256                    }
6257                }),
6258        )
6259    }
6260
6261    /// Returns enclosing bracket ranges containing the given range or returns None if the range is
6262    /// not contained in a single excerpt
6263    pub fn text_object_ranges<T: ToOffset>(
6264        &self,
6265        range: Range<T>,
6266        options: TreeSitterOptions,
6267    ) -> impl Iterator<Item = (Range<MultiBufferOffset>, TextObject)> + '_ {
6268        let range = range.start.to_offset(self)..range.end.to_offset(self);
6269        self.excerpt_containing(range.clone())
6270            .map(|mut excerpt| {
6271                excerpt
6272                    .buffer()
6273                    .text_object_ranges(excerpt.map_range_to_buffer(range), options)
6274                    .filter_map(move |(range, text_object)| {
6275                        let range = BufferOffset(range.start)..BufferOffset(range.end);
6276                        if excerpt.contains_buffer_range(range.clone()) {
6277                            Some((excerpt.map_range_from_buffer(range), text_object))
6278                        } else {
6279                            None
6280                        }
6281                    })
6282            })
6283            .into_iter()
6284            .flatten()
6285    }
6286
6287    /// Returns bracket range pairs overlapping the given `range` or returns None if the `range` is
6288    /// not contained in a single excerpt
6289    pub fn bracket_ranges<T: ToOffset>(
6290        &self,
6291        range: Range<T>,
6292    ) -> Option<impl Iterator<Item = (Range<MultiBufferOffset>, Range<MultiBufferOffset>)> + '_>
6293    {
6294        let range = range.start.to_offset(self)..range.end.to_offset(self);
6295        let mut excerpt = self.excerpt_containing(range.clone())?;
6296        Some(
6297            excerpt
6298                .buffer()
6299                .bracket_ranges(excerpt.map_range_to_buffer(range))
6300                .filter_map(move |pair| {
6301                    let open_range =
6302                        BufferOffset(pair.open_range.start)..BufferOffset(pair.open_range.end);
6303                    let close_range =
6304                        BufferOffset(pair.close_range.start)..BufferOffset(pair.close_range.end);
6305                    excerpt
6306                        .contains_buffer_range(open_range.start..close_range.end)
6307                        .then(|| BracketMatch {
6308                            open_range: excerpt.map_range_from_buffer(open_range),
6309                            close_range: excerpt.map_range_from_buffer(close_range),
6310                            color_index: pair.color_index,
6311                            newline_only: pair.newline_only,
6312                            syntax_layer_depth: pair.syntax_layer_depth,
6313                        })
6314                })
6315                .map(BracketMatch::bracket_ranges),
6316        )
6317    }
6318
6319    pub fn redacted_ranges<'a, T: ToOffset>(
6320        &'a self,
6321        range: Range<T>,
6322        redaction_enabled: impl Fn(Option<&Arc<dyn File>>) -> bool + 'a,
6323    ) -> impl Iterator<Item = Range<MultiBufferOffset>> + 'a {
6324        let range = range.start.to_offset(self)..range.end.to_offset(self);
6325        self.lift_buffer_metadata(range, move |buffer, range| {
6326            if redaction_enabled(buffer.file()) {
6327                Some(buffer.redacted_ranges(range).map(|range| (range, ())))
6328            } else {
6329                None
6330            }
6331        })
6332        .map(|(range, _, _)| range)
6333    }
6334
6335    pub fn runnable_ranges(
6336        &self,
6337        range: Range<Anchor>,
6338    ) -> impl Iterator<Item = (Range<MultiBufferOffset>, language::RunnableRange)> + '_ {
6339        let range = range.start.to_offset(self)..range.end.to_offset(self);
6340        self.lift_buffer_metadata(range, move |buffer, range| {
6341            Some(
6342                buffer
6343                    .runnable_ranges(range.clone())
6344                    .filter(move |runnable| {
6345                        runnable.run_range.start >= range.start
6346                            && runnable.run_range.end < range.end
6347                    })
6348                    .map(|runnable| (runnable.run_range.clone(), runnable)),
6349            )
6350        })
6351        .map(|(run_range, runnable, _)| (run_range, runnable))
6352    }
6353
6354    pub fn line_indents(
6355        &self,
6356        start_row: MultiBufferRow,
6357        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
6358    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
6359        let max_point = self.max_point();
6360        let mut cursor = self.cursor::<Point, Point>();
6361        cursor.seek(&Point::new(start_row.0, 0));
6362        iter::from_fn(move || {
6363            let mut region = cursor.region()?;
6364            while !buffer_filter(&region.excerpt.buffer) {
6365                cursor.next();
6366                region = cursor.region()?;
6367            }
6368            let region = cursor.region()?;
6369            let overshoot = start_row.0.saturating_sub(region.range.start.row);
6370            let buffer_start_row =
6371                (region.buffer_range.start.row + overshoot).min(region.buffer_range.end.row);
6372
6373            let buffer_end_row = if region.is_main_buffer
6374                && (region.has_trailing_newline || region.range.end == max_point)
6375            {
6376                region.buffer_range.end.row
6377            } else {
6378                region.buffer_range.end.row.saturating_sub(1)
6379            };
6380
6381            let line_indents = region
6382                .buffer
6383                .line_indents_in_row_range(buffer_start_row..buffer_end_row);
6384            let region_buffer_row = region.buffer_range.start.row;
6385            let region_row = region.range.start.row;
6386            let region_buffer = &region.excerpt.buffer;
6387            cursor.next();
6388            Some(line_indents.map(move |(buffer_row, indent)| {
6389                let row = region_row + (buffer_row - region_buffer_row);
6390                (MultiBufferRow(row), indent, region_buffer.as_ref())
6391            }))
6392        })
6393        .flatten()
6394    }
6395
6396    pub fn reversed_line_indents(
6397        &self,
6398        end_row: MultiBufferRow,
6399        buffer_filter: impl Fn(&BufferSnapshot) -> bool,
6400    ) -> impl Iterator<Item = (MultiBufferRow, LineIndent, &BufferSnapshot)> {
6401        let max_point = self.max_point();
6402        let mut cursor = self.cursor::<Point, Point>();
6403        cursor.seek(&Point::new(end_row.0, 0));
6404        iter::from_fn(move || {
6405            let mut region = cursor.region()?;
6406            while !buffer_filter(&region.excerpt.buffer) {
6407                cursor.prev();
6408                region = cursor.region()?;
6409            }
6410            let region = cursor.region()?;
6411
6412            let buffer_start_row = region.buffer_range.start.row;
6413            let buffer_end_row = if region.is_main_buffer
6414                && (region.has_trailing_newline || region.range.end == max_point)
6415            {
6416                region.buffer_range.end.row + 1
6417            } else {
6418                region.buffer_range.end.row
6419            };
6420
6421            let overshoot = end_row.0 - region.range.start.row;
6422            let buffer_end_row =
6423                (region.buffer_range.start.row + overshoot + 1).min(buffer_end_row);
6424
6425            let line_indents = region
6426                .buffer
6427                .reversed_line_indents_in_row_range(buffer_start_row..buffer_end_row);
6428            let region_buffer_row = region.buffer_range.start.row;
6429            let region_row = region.range.start.row;
6430            let region_buffer = &region.excerpt.buffer;
6431            cursor.prev();
6432            Some(line_indents.map(move |(buffer_row, indent)| {
6433                let row = region_row + (buffer_row - region_buffer_row);
6434                (MultiBufferRow(row), indent, region_buffer.as_ref())
6435            }))
6436        })
6437        .flatten()
6438    }
6439
6440    pub async fn enclosing_indent(
6441        &self,
6442        mut target_row: MultiBufferRow,
6443    ) -> Option<(Range<MultiBufferRow>, LineIndent)> {
6444        let max_row = MultiBufferRow(self.max_point().row);
6445        if target_row >= max_row {
6446            return None;
6447        }
6448
6449        let mut target_indent = self.line_indent_for_row(target_row);
6450
6451        // If the current row is at the start of an indented block, we want to return this
6452        // block as the enclosing indent.
6453        if !target_indent.is_line_empty() && target_row < max_row {
6454            let next_line_indent = self.line_indent_for_row(MultiBufferRow(target_row.0 + 1));
6455            if !next_line_indent.is_line_empty()
6456                && target_indent.raw_len() < next_line_indent.raw_len()
6457            {
6458                target_indent = next_line_indent;
6459                target_row.0 += 1;
6460            }
6461        }
6462
6463        const SEARCH_ROW_LIMIT: u32 = 25000;
6464        const SEARCH_WHITESPACE_ROW_LIMIT: u32 = 2500;
6465        const YIELD_INTERVAL: u32 = 100;
6466
6467        let mut accessed_row_counter = 0;
6468
6469        // If there is a blank line at the current row, search for the next non indented lines
6470        if target_indent.is_line_empty() {
6471            let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_WHITESPACE_ROW_LIMIT));
6472            let end =
6473                MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_WHITESPACE_ROW_LIMIT));
6474
6475            let mut non_empty_line_above = None;
6476            for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
6477                if row < start {
6478                    break;
6479                }
6480                accessed_row_counter += 1;
6481                if accessed_row_counter == YIELD_INTERVAL {
6482                    accessed_row_counter = 0;
6483                    yield_now().await;
6484                }
6485                if !indent.is_line_empty() {
6486                    non_empty_line_above = Some((row, indent));
6487                    break;
6488                }
6489            }
6490
6491            let mut non_empty_line_below = None;
6492            for (row, indent, _) in self.line_indents(target_row, |_| true) {
6493                if row > end {
6494                    break;
6495                }
6496                accessed_row_counter += 1;
6497                if accessed_row_counter == YIELD_INTERVAL {
6498                    accessed_row_counter = 0;
6499                    yield_now().await;
6500                }
6501                if !indent.is_line_empty() {
6502                    non_empty_line_below = Some((row, indent));
6503                    break;
6504                }
6505            }
6506
6507            let (row, indent) = match (non_empty_line_above, non_empty_line_below) {
6508                (Some((above_row, above_indent)), Some((below_row, below_indent))) => {
6509                    if above_indent.raw_len() >= below_indent.raw_len() {
6510                        (above_row, above_indent)
6511                    } else {
6512                        (below_row, below_indent)
6513                    }
6514                }
6515                (Some(above), None) => above,
6516                (None, Some(below)) => below,
6517                _ => return None,
6518            };
6519
6520            target_indent = indent;
6521            target_row = row;
6522        }
6523
6524        let start = MultiBufferRow(target_row.0.saturating_sub(SEARCH_ROW_LIMIT));
6525        let end = MultiBufferRow((max_row.0 + 1).min(target_row.0 + SEARCH_ROW_LIMIT));
6526
6527        let mut start_indent = None;
6528        for (row, indent, _) in self.reversed_line_indents(target_row, |_| true) {
6529            if row < start {
6530                break;
6531            }
6532            accessed_row_counter += 1;
6533            if accessed_row_counter == YIELD_INTERVAL {
6534                accessed_row_counter = 0;
6535                yield_now().await;
6536            }
6537            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
6538                start_indent = Some((row, indent));
6539                break;
6540            }
6541        }
6542        let (start_row, start_indent_size) = start_indent?;
6543
6544        let mut end_indent = (end, None);
6545        for (row, indent, _) in self.line_indents(target_row, |_| true) {
6546            if row > end {
6547                break;
6548            }
6549            accessed_row_counter += 1;
6550            if accessed_row_counter == YIELD_INTERVAL {
6551                accessed_row_counter = 0;
6552                yield_now().await;
6553            }
6554            if !indent.is_line_empty() && indent.raw_len() < target_indent.raw_len() {
6555                end_indent = (MultiBufferRow(row.0.saturating_sub(1)), Some(indent));
6556                break;
6557            }
6558        }
6559        let (end_row, end_indent_size) = end_indent;
6560
6561        let indent = if let Some(end_indent_size) = end_indent_size {
6562            if start_indent_size.raw_len() > end_indent_size.raw_len() {
6563                start_indent_size
6564            } else {
6565                end_indent_size
6566            }
6567        } else {
6568            start_indent_size
6569        };
6570
6571        Some((start_row..end_row, indent))
6572    }
6573
6574    pub fn indent_guides_in_range<T: ToPoint>(
6575        &self,
6576        range: Range<T>,
6577        ignore_disabled_for_language: bool,
6578        cx: &App,
6579    ) -> impl Iterator<Item = IndentGuide> {
6580        let range = range.start.to_point(self)..range.end.to_point(self);
6581        let start_row = MultiBufferRow(range.start.row);
6582        let end_row = MultiBufferRow(range.end.row);
6583
6584        let mut row_indents = self.line_indents(start_row, |buffer| {
6585            let settings =
6586                language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx);
6587            settings.indent_guides.enabled || ignore_disabled_for_language
6588        });
6589
6590        let mut result = Vec::new();
6591        let mut indent_stack = SmallVec::<[IndentGuide; 8]>::new();
6592
6593        let mut prev_settings = None;
6594        while let Some((first_row, mut line_indent, buffer)) = row_indents.next() {
6595            if first_row > end_row {
6596                break;
6597            }
6598            let current_depth = indent_stack.len() as u32;
6599
6600            // Avoid retrieving the language settings repeatedly for every buffer row.
6601            if let Some((prev_buffer_id, _)) = &prev_settings
6602                && prev_buffer_id != &buffer.remote_id()
6603            {
6604                prev_settings.take();
6605            }
6606            let settings = &prev_settings
6607                .get_or_insert_with(|| {
6608                    (
6609                        buffer.remote_id(),
6610                        language_settings(buffer.language().map(|l| l.name()), buffer.file(), cx),
6611                    )
6612                })
6613                .1;
6614            let tab_size = settings.tab_size.get();
6615
6616            // When encountering empty, continue until found useful line indent
6617            // then add to the indent stack with the depth found
6618            let mut found_indent = false;
6619            let mut last_row = first_row;
6620            if line_indent.is_line_blank() {
6621                while !found_indent {
6622                    let Some((target_row, new_line_indent, _)) = row_indents.next() else {
6623                        break;
6624                    };
6625                    const TRAILING_ROW_SEARCH_LIMIT: u32 = 25;
6626                    if target_row > MultiBufferRow(end_row.0 + TRAILING_ROW_SEARCH_LIMIT) {
6627                        break;
6628                    }
6629
6630                    if new_line_indent.is_line_blank() {
6631                        continue;
6632                    }
6633                    last_row = target_row.min(end_row);
6634                    line_indent = new_line_indent;
6635                    found_indent = true;
6636                    break;
6637                }
6638            } else {
6639                found_indent = true
6640            }
6641
6642            let depth = if found_indent {
6643                line_indent.len(tab_size) / tab_size
6644            } else {
6645                0
6646            };
6647
6648            match depth.cmp(&current_depth) {
6649                cmp::Ordering::Less => {
6650                    for _ in 0..(current_depth - depth) {
6651                        let mut indent = indent_stack.pop().unwrap();
6652                        if last_row != first_row {
6653                            // In this case, we landed on an empty row, had to seek forward,
6654                            // and discovered that the indent we where on is ending.
6655                            // This means that the last display row must
6656                            // be on line that ends this indent range, so we
6657                            // should display the range up to the first non-empty line
6658                            indent.end_row = MultiBufferRow(first_row.0.saturating_sub(1));
6659                        }
6660
6661                        result.push(indent)
6662                    }
6663                }
6664                cmp::Ordering::Greater => {
6665                    for next_depth in current_depth..depth {
6666                        indent_stack.push(IndentGuide {
6667                            buffer_id: buffer.remote_id(),
6668                            start_row: first_row,
6669                            end_row: last_row,
6670                            depth: next_depth,
6671                            tab_size,
6672                            settings: settings.indent_guides.clone(),
6673                        });
6674                    }
6675                }
6676                _ => {}
6677            }
6678
6679            for indent in indent_stack.iter_mut() {
6680                indent.end_row = last_row;
6681            }
6682        }
6683
6684        result.extend(indent_stack);
6685        result.into_iter()
6686    }
6687
6688    pub fn trailing_excerpt_update_count(&self) -> usize {
6689        self.trailing_excerpt_update_count
6690    }
6691
6692    pub fn file_at<T: ToOffset>(&self, point: T) -> Option<&Arc<dyn File>> {
6693        self.point_to_buffer_offset(point)
6694            .and_then(|(buffer, _)| buffer.file())
6695    }
6696
6697    pub fn language_at<T: ToOffset>(&self, offset: T) -> Option<&Arc<Language>> {
6698        self.point_to_buffer_offset(offset)
6699            .and_then(|(buffer, offset)| buffer.language_at(offset))
6700    }
6701
6702    fn language_settings<'a>(&'a self, cx: &'a App) -> Cow<'a, LanguageSettings> {
6703        self.excerpts
6704            .first()
6705            .map(|excerpt| &excerpt.buffer)
6706            .map(|buffer| {
6707                language_settings(
6708                    buffer.language().map(|language| language.name()),
6709                    buffer.file(),
6710                    cx,
6711                )
6712            })
6713            .unwrap_or_else(move || self.language_settings_at(MultiBufferOffset::ZERO, cx))
6714    }
6715
6716    pub fn language_settings_at<'a, T: ToOffset>(
6717        &'a self,
6718        point: T,
6719        cx: &'a App,
6720    ) -> Cow<'a, LanguageSettings> {
6721        let mut language = None;
6722        let mut file = None;
6723        if let Some((buffer, offset)) = self.point_to_buffer_offset(point) {
6724            language = buffer.language_at(offset);
6725            file = buffer.file();
6726        }
6727        language_settings(language.map(|l| l.name()), file, cx)
6728    }
6729
6730    pub fn language_scope_at<T: ToOffset>(&self, point: T) -> Option<LanguageScope> {
6731        self.point_to_buffer_offset(point)
6732            .and_then(|(buffer, offset)| buffer.language_scope_at(offset))
6733    }
6734
6735    pub fn char_classifier_at<T: ToOffset>(&self, point: T) -> CharClassifier {
6736        self.point_to_buffer_offset(point)
6737            .map(|(buffer, offset)| buffer.char_classifier_at(offset))
6738            .unwrap_or_default()
6739    }
6740
6741    pub fn language_indent_size_at<T: ToOffset>(
6742        &self,
6743        position: T,
6744        cx: &App,
6745    ) -> Option<IndentSize> {
6746        let (buffer_snapshot, offset) = self.point_to_buffer_offset(position)?;
6747        Some(buffer_snapshot.language_indent_size_at(offset, cx))
6748    }
6749
6750    pub fn is_dirty(&self) -> bool {
6751        self.is_dirty
6752    }
6753
6754    pub fn has_deleted_file(&self) -> bool {
6755        self.has_deleted_file
6756    }
6757
6758    pub fn has_conflict(&self) -> bool {
6759        self.has_conflict
6760    }
6761
6762    pub fn has_diagnostics(&self) -> bool {
6763        self.excerpts
6764            .iter()
6765            .any(|excerpt| excerpt.buffer.has_diagnostics())
6766    }
6767
6768    pub fn diagnostic_group(
6769        &self,
6770        buffer_id: BufferId,
6771        group_id: usize,
6772    ) -> impl Iterator<Item = DiagnosticEntryRef<'_, Point>> + '_ {
6773        self.lift_buffer_metadata::<Point, _, _>(
6774            Point::zero()..self.max_point(),
6775            move |buffer, range| {
6776                if buffer.remote_id() != buffer_id {
6777                    return None;
6778                };
6779                Some(
6780                    buffer
6781                        .diagnostics_in_range(range, false)
6782                        .filter(move |diagnostic| diagnostic.diagnostic.group_id == group_id)
6783                        .map(move |DiagnosticEntryRef { diagnostic, range }| (range, diagnostic)),
6784                )
6785            },
6786        )
6787        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
6788    }
6789
6790    pub fn diagnostics_in_range<'a, MBD>(
6791        &'a self,
6792        range: Range<MBD>,
6793    ) -> impl Iterator<Item = DiagnosticEntryRef<'a, MBD>> + 'a
6794    where
6795        MBD::TextDimension: 'a
6796            + text::ToOffset
6797            + text::FromAnchor
6798            + Sub<Output = MBD::TextDimension>
6799            + fmt::Debug
6800            + ops::Add<Output = MBD::TextDimension>
6801            + ops::AddAssign
6802            + Ord,
6803        MBD: MultiBufferDimension
6804            + Ord
6805            + Sub<Output = MBD::TextDimension>
6806            + ops::Add<MBD::TextDimension, Output = MBD>
6807            + ops::AddAssign<MBD::TextDimension>
6808            + 'a,
6809    {
6810        self.lift_buffer_metadata::<MBD, _, _>(range, move |buffer, buffer_range| {
6811            Some(
6812                buffer
6813                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6814                    .map(|entry| (entry.range, entry.diagnostic)),
6815            )
6816        })
6817        .map(|(range, diagnostic, _)| DiagnosticEntryRef { diagnostic, range })
6818    }
6819
6820    pub fn diagnostics_with_buffer_ids_in_range<'a, MBD>(
6821        &'a self,
6822        range: Range<MBD>,
6823    ) -> impl Iterator<Item = (BufferId, DiagnosticEntryRef<'a, MBD>)> + 'a
6824    where
6825        MBD: MultiBufferDimension
6826            + Ord
6827            + Sub<Output = MBD::TextDimension>
6828            + ops::Add<MBD::TextDimension, Output = MBD>
6829            + ops::AddAssign<MBD::TextDimension>,
6830        MBD::TextDimension: Sub<Output = MBD::TextDimension>
6831            + ops::Add<Output = MBD::TextDimension>
6832            + text::ToOffset
6833            + text::FromAnchor
6834            + AddAssign<MBD::TextDimension>
6835            + Ord,
6836    {
6837        self.lift_buffer_metadata::<MBD, _, _>(range, move |buffer, buffer_range| {
6838            Some(
6839                buffer
6840                    .diagnostics_in_range(buffer_range.start..buffer_range.end, false)
6841                    .map(|entry| (entry.range, entry.diagnostic)),
6842            )
6843        })
6844        .map(|(range, diagnostic, b)| (b.buffer_id, DiagnosticEntryRef { diagnostic, range }))
6845    }
6846
6847    pub fn syntax_ancestor<T: ToOffset>(
6848        &self,
6849        range: Range<T>,
6850    ) -> Option<(tree_sitter::Node<'_>, Range<MultiBufferOffset>)> {
6851        let range = range.start.to_offset(self)..range.end.to_offset(self);
6852        let mut excerpt = self.excerpt_containing(range.clone())?;
6853        let node = excerpt
6854            .buffer()
6855            .syntax_ancestor(excerpt.map_range_to_buffer(range))?;
6856        let node_range = node.byte_range();
6857        let node_range = BufferOffset(node_range.start)..BufferOffset(node_range.end);
6858        if !excerpt.contains_buffer_range(node_range.clone()) {
6859            return None;
6860        };
6861        Some((node, excerpt.map_range_from_buffer(node_range)))
6862    }
6863
6864    pub fn outline(&self, theme: Option<&SyntaxTheme>) -> Option<Outline<Anchor>> {
6865        let (excerpt_id, _, buffer) = self.as_singleton()?;
6866        let outline = buffer.outline(theme);
6867        Some(Outline::new(
6868            outline
6869                .items
6870                .into_iter()
6871                .flat_map(|item| {
6872                    Some(OutlineItem {
6873                        depth: item.depth,
6874                        range: self.anchor_range_in_excerpt(excerpt_id, item.range)?,
6875                        source_range_for_text: self
6876                            .anchor_range_in_excerpt(excerpt_id, item.source_range_for_text)?,
6877                        text: item.text,
6878                        highlight_ranges: item.highlight_ranges,
6879                        name_ranges: item.name_ranges,
6880                        body_range: item.body_range.and_then(|body_range| {
6881                            self.anchor_range_in_excerpt(excerpt_id, body_range)
6882                        }),
6883                        annotation_range: item.annotation_range.and_then(|annotation_range| {
6884                            self.anchor_range_in_excerpt(excerpt_id, annotation_range)
6885                        }),
6886                    })
6887                })
6888                .collect(),
6889        ))
6890    }
6891
6892    pub fn symbols_containing<T: ToOffset>(
6893        &self,
6894        offset: T,
6895        theme: Option<&SyntaxTheme>,
6896    ) -> Option<(BufferId, Vec<OutlineItem<Anchor>>)> {
6897        let anchor = self.anchor_before(offset);
6898        let excerpt @ &Excerpt {
6899            id: excerpt_id,
6900            buffer_id,
6901            ref buffer,
6902            ..
6903        } = self.excerpt(anchor.excerpt_id)?;
6904        if cfg!(debug_assertions) {
6905            match anchor.text_anchor.buffer_id {
6906                // we clearly are hitting this according to sentry, but in what situations can this occur?
6907                Some(anchor_buffer_id) => {
6908                    assert_eq!(
6909                        anchor_buffer_id, buffer_id,
6910                        "anchor {anchor:?} does not match with resolved excerpt {excerpt:?}"
6911                    )
6912                }
6913                None => assert!(anchor.is_max()),
6914            }
6915        };
6916        Some((
6917            buffer_id,
6918            buffer
6919                .symbols_containing(anchor.text_anchor, theme)
6920                .into_iter()
6921                .flat_map(|item| {
6922                    Some(OutlineItem {
6923                        depth: item.depth,
6924                        source_range_for_text: Anchor::range_in_buffer(
6925                            excerpt_id,
6926                            item.source_range_for_text,
6927                        ),
6928                        range: Anchor::range_in_buffer(excerpt_id, item.range),
6929                        text: item.text,
6930                        highlight_ranges: item.highlight_ranges,
6931                        name_ranges: item.name_ranges,
6932                        body_range: item
6933                            .body_range
6934                            .map(|body_range| Anchor::range_in_buffer(excerpt_id, body_range)),
6935                        annotation_range: item
6936                            .annotation_range
6937                            .map(|body_range| Anchor::range_in_buffer(excerpt_id, body_range)),
6938                    })
6939                })
6940                .collect(),
6941        ))
6942    }
6943
6944    fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
6945        self.try_excerpt_locator_for_id(id)
6946            .unwrap_or_else(|| panic!("invalid excerpt id {id:?}"))
6947    }
6948
6949    fn try_excerpt_locator_for_id(&self, id: ExcerptId) -> Option<&Locator> {
6950        if id == ExcerptId::min() {
6951            Some(Locator::min_ref())
6952        } else if id == ExcerptId::max() {
6953            Some(Locator::max_ref())
6954        } else {
6955            let (_, _, item) = self.excerpt_ids.find::<ExcerptId, _>((), &id, Bias::Left);
6956            if let Some(entry) = item
6957                && entry.id == id
6958            {
6959                return Some(&entry.locator);
6960            }
6961            None
6962        }
6963    }
6964
6965    /// Returns the locators referenced by the given excerpt IDs, sorted by locator.
6966    fn excerpt_locators_for_ids(
6967        &self,
6968        ids: impl IntoIterator<Item = ExcerptId>,
6969    ) -> SmallVec<[Locator; 1]> {
6970        let mut sorted_ids = ids.into_iter().collect::<SmallVec<[_; 1]>>();
6971        sorted_ids.sort_unstable();
6972        sorted_ids.dedup();
6973        let mut locators = SmallVec::new();
6974
6975        while sorted_ids.last() == Some(&ExcerptId::max()) {
6976            sorted_ids.pop();
6977            locators.push(Locator::max());
6978        }
6979
6980        let mut sorted_ids = sorted_ids.into_iter().peekable();
6981        locators.extend(
6982            sorted_ids
6983                .peeking_take_while(|excerpt| *excerpt == ExcerptId::min())
6984                .map(|_| Locator::min()),
6985        );
6986
6987        let mut cursor = self.excerpt_ids.cursor::<ExcerptId>(());
6988        for id in sorted_ids {
6989            if cursor.seek_forward(&id, Bias::Left) {
6990                locators.push(cursor.item().unwrap().locator.clone());
6991            } else {
6992                panic!("invalid excerpt id {:?}", id);
6993            }
6994        }
6995
6996        locators.sort_unstable();
6997        locators
6998    }
6999
7000    pub fn buffer_id_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<BufferId> {
7001        Some(self.excerpt(excerpt_id)?.buffer_id)
7002    }
7003
7004    pub fn buffer_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<&BufferSnapshot> {
7005        Some(&self.excerpt(excerpt_id)?.buffer)
7006    }
7007
7008    pub fn range_for_excerpt(&self, excerpt_id: ExcerptId) -> Option<Range<Point>> {
7009        let mut cursor = self
7010            .excerpts
7011            .cursor::<Dimensions<Option<&Locator>, ExcerptPoint>>(());
7012        let locator = self.excerpt_locator_for_id(excerpt_id);
7013        let mut sought_exact = cursor.seek(&Some(locator), Bias::Left);
7014        if cursor.item().is_none() && excerpt_id == ExcerptId::max() {
7015            sought_exact = true;
7016            cursor.prev();
7017        } else if excerpt_id == ExcerptId::min() {
7018            sought_exact = true;
7019        }
7020        if sought_exact {
7021            let start = cursor.start().1;
7022            let end = cursor.end().1;
7023            let mut diff_transforms = self
7024                .diff_transforms
7025                .cursor::<Dimensions<ExcerptPoint, OutputDimension<Point>>>(());
7026            diff_transforms.seek(&start, Bias::Left);
7027            let overshoot = start - diff_transforms.start().0;
7028            let start = diff_transforms.start().1 + overshoot;
7029            diff_transforms.seek(&end, Bias::Right);
7030            let overshoot = end - diff_transforms.start().0;
7031            let end = diff_transforms.start().1 + overshoot;
7032            Some(start.0..end.0)
7033        } else {
7034            None
7035        }
7036    }
7037
7038    /// Returns the excerpt for the given id. The returned excerpt is guaranteed
7039    /// to have the latest excerpt id for the one passed in and will also remap
7040    /// `ExcerptId::max()` to the corresponding excertp ID.
7041    ///
7042    /// Callers of this function should generally use the resulting excerpt's `id` field
7043    /// afterwards.
7044    fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
7045        let excerpt_id = self.latest_excerpt_id(excerpt_id);
7046        let locator = self.try_excerpt_locator_for_id(excerpt_id)?;
7047        let (_, _, item) =
7048            self.excerpts
7049                .find::<Option<&Locator>, _>((), &Some(locator), Bias::Left);
7050        if let Some(excerpt) = item
7051            && excerpt.id == excerpt_id
7052        {
7053            return Some(excerpt);
7054        } else if item.is_none() && excerpt_id == ExcerptId::max() {
7055            return self.excerpts.last();
7056        }
7057        None
7058    }
7059
7060    /// Returns the excerpt containing range and its offset start within the multibuffer or none if `range` spans multiple excerpts
7061    pub fn excerpt_containing<T: ToOffset>(
7062        &self,
7063        range: Range<T>,
7064    ) -> Option<MultiBufferExcerpt<'_>> {
7065        let range = range.start.to_offset(self)..range.end.to_offset(self);
7066        let mut cursor = self.cursor::<MultiBufferOffset, BufferOffset>();
7067        cursor.seek(&range.start);
7068
7069        let start_excerpt = cursor.excerpt()?;
7070        if range.end != range.start {
7071            cursor.seek_forward(&range.end);
7072            if cursor.excerpt()?.id != start_excerpt.id {
7073                return None;
7074            }
7075        }
7076
7077        cursor.seek_to_start_of_current_excerpt();
7078        let region = cursor.region()?;
7079        let offset = region.range.start;
7080        let buffer_offset = start_excerpt.buffer_start_offset();
7081        let excerpt_offset = *cursor.excerpts.start();
7082        Some(MultiBufferExcerpt {
7083            diff_transforms: cursor.diff_transforms,
7084            excerpt: start_excerpt,
7085            offset,
7086            buffer_offset,
7087            excerpt_offset,
7088        })
7089    }
7090
7091    pub fn buffer_id_for_anchor(&self, anchor: Anchor) -> Option<BufferId> {
7092        if let Some(id) = anchor.text_anchor.buffer_id {
7093            return Some(id);
7094        }
7095        let excerpt = self.excerpt_containing(anchor..anchor)?;
7096        Some(excerpt.buffer_id())
7097    }
7098
7099    pub fn selections_in_range<'a>(
7100        &'a self,
7101        range: &'a Range<Anchor>,
7102        include_local: bool,
7103    ) -> impl 'a + Iterator<Item = (ReplicaId, bool, CursorShape, Selection<Anchor>)> {
7104        let mut cursor = self.excerpts.cursor::<ExcerptSummary>(());
7105        let start_locator = self.excerpt_locator_for_id(range.start.excerpt_id);
7106        let end_locator = self.excerpt_locator_for_id(range.end.excerpt_id);
7107        cursor.seek(start_locator, Bias::Left);
7108        cursor
7109            .take_while(move |excerpt| excerpt.locator <= *end_locator)
7110            .flat_map(move |excerpt| {
7111                let mut query_range = excerpt.range.context.start..excerpt.range.context.end;
7112                if excerpt.id == range.start.excerpt_id {
7113                    query_range.start = range.start.text_anchor;
7114                }
7115                if excerpt.id == range.end.excerpt_id {
7116                    query_range.end = range.end.text_anchor;
7117                }
7118
7119                excerpt
7120                    .buffer
7121                    .selections_in_range(query_range, include_local)
7122                    .flat_map(move |(replica_id, line_mode, cursor_shape, selections)| {
7123                        selections.map(move |selection| {
7124                            let mut start = Anchor::in_buffer(excerpt.id, selection.start);
7125                            let mut end = Anchor::in_buffer(excerpt.id, selection.end);
7126                            if range.start.cmp(&start, self).is_gt() {
7127                                start = range.start;
7128                            }
7129                            if range.end.cmp(&end, self).is_lt() {
7130                                end = range.end;
7131                            }
7132
7133                            (
7134                                replica_id,
7135                                line_mode,
7136                                cursor_shape,
7137                                Selection {
7138                                    id: selection.id,
7139                                    start,
7140                                    end,
7141                                    reversed: selection.reversed,
7142                                    goal: selection.goal,
7143                                },
7144                            )
7145                        })
7146                    })
7147            })
7148    }
7149
7150    pub fn show_headers(&self) -> bool {
7151        self.show_headers
7152    }
7153
7154    pub fn diff_for_buffer_id(&self, buffer_id: BufferId) -> Option<&BufferDiffSnapshot> {
7155        self.diffs.get(&buffer_id).map(|diff| &diff.diff)
7156    }
7157
7158    pub fn all_diff_hunks_expanded(&self) -> bool {
7159        self.all_diff_hunks_expanded
7160    }
7161
7162    /// Visually annotates a position or range with the `Debug` representation of a value. The
7163    /// callsite of this function is used as a key - previous annotations will be removed.
7164    #[cfg(debug_assertions)]
7165    #[track_caller]
7166    pub fn debug<V, R>(&self, ranges: &R, value: V)
7167    where
7168        R: debug::ToMultiBufferDebugRanges,
7169        V: std::fmt::Debug,
7170    {
7171        self.debug_with_key(std::panic::Location::caller(), ranges, value);
7172    }
7173
7174    /// Visually annotates a position or range with the `Debug` representation of a value. Previous
7175    /// debug annotations with the same key will be removed. The key is also used to determine the
7176    /// annotation's color.
7177    #[cfg(debug_assertions)]
7178    #[track_caller]
7179    pub fn debug_with_key<K, R, V>(&self, key: &K, ranges: &R, value: V)
7180    where
7181        K: std::hash::Hash + 'static,
7182        R: debug::ToMultiBufferDebugRanges,
7183        V: std::fmt::Debug,
7184    {
7185        let text_ranges = ranges
7186            .to_multi_buffer_debug_ranges(self)
7187            .into_iter()
7188            .flat_map(|range| {
7189                self.range_to_buffer_ranges(range.start..=range.end)
7190                    .into_iter()
7191                    .map(|(buffer, range, _excerpt_id)| {
7192                        buffer.anchor_after(range.start)..buffer.anchor_before(range.end)
7193                    })
7194            })
7195            .collect();
7196        text::debug::GlobalDebugRanges::with_locked(|debug_ranges| {
7197            debug_ranges.insert(key, text_ranges, format!("{value:?}").into())
7198        });
7199    }
7200
7201    fn excerpt_edits_for_diff_change(
7202        &self,
7203        buffer_state: &BufferState,
7204        diff_change_range: Range<usize>,
7205    ) -> Vec<Edit<ExcerptDimension<MultiBufferOffset>>> {
7206        let mut excerpt_edits = Vec::new();
7207        for locator in &buffer_state.excerpts {
7208            let mut cursor = self
7209                .excerpts
7210                .cursor::<Dimensions<Option<&Locator>, ExcerptOffset>>(());
7211            cursor.seek_forward(&Some(locator), Bias::Left);
7212            if let Some(excerpt) = cursor.item()
7213                && excerpt.locator == *locator
7214            {
7215                let excerpt_buffer_range = excerpt.range.context.to_offset(&excerpt.buffer);
7216                if diff_change_range.end < excerpt_buffer_range.start
7217                    || diff_change_range.start > excerpt_buffer_range.end
7218                {
7219                    continue;
7220                }
7221                let excerpt_start = cursor.start().1;
7222                let excerpt_len = excerpt.text_summary.len;
7223                let diff_change_start_in_excerpt = diff_change_range
7224                    .start
7225                    .saturating_sub(excerpt_buffer_range.start);
7226                let diff_change_end_in_excerpt = diff_change_range
7227                    .end
7228                    .saturating_sub(excerpt_buffer_range.start);
7229                let edit_start = excerpt_start + diff_change_start_in_excerpt.min(excerpt_len);
7230                let edit_end = excerpt_start + diff_change_end_in_excerpt.min(excerpt_len);
7231                excerpt_edits.push(Edit {
7232                    old: edit_start..edit_end,
7233                    new: edit_start..edit_end,
7234                });
7235            }
7236        }
7237        excerpt_edits
7238    }
7239}
7240
7241#[cfg(any(test, feature = "test-support"))]
7242impl MultiBufferSnapshot {
7243    pub fn random_byte_range(
7244        &self,
7245        start_offset: MultiBufferOffset,
7246        rng: &mut impl rand::Rng,
7247    ) -> Range<MultiBufferOffset> {
7248        let end = self.clip_offset(rng.random_range(start_offset..=self.len()), Bias::Right);
7249        let start = self.clip_offset(rng.random_range(start_offset..=end), Bias::Right);
7250        start..end
7251    }
7252
7253    #[cfg(any(test, feature = "test-support"))]
7254    fn check_invariants(&self) {
7255        let excerpts = self.excerpts.items(());
7256        let excerpt_ids = self.excerpt_ids.items(());
7257
7258        for (ix, excerpt) in excerpts.iter().enumerate() {
7259            if ix == 0 {
7260                if excerpt.locator <= Locator::min() {
7261                    panic!("invalid first excerpt locator {:?}", excerpt.locator);
7262                }
7263            } else if excerpt.locator <= excerpts[ix - 1].locator {
7264                panic!("excerpts are out-of-order: {:?}", excerpts);
7265            }
7266        }
7267
7268        for (ix, entry) in excerpt_ids.iter().enumerate() {
7269            if ix == 0 {
7270                if entry.id.cmp(&ExcerptId::min(), self).is_le() {
7271                    panic!("invalid first excerpt id {:?}", entry.id);
7272                }
7273            } else if entry.id <= excerpt_ids[ix - 1].id {
7274                panic!("excerpt ids are out-of-order: {:?}", excerpt_ids);
7275            }
7276        }
7277
7278        if self.diff_transforms.summary().input != self.excerpts.summary().text {
7279            panic!(
7280                "incorrect input summary. expected {:?}, got {:?}. transforms: {:+?}",
7281                self.excerpts.summary().text,
7282                self.diff_transforms.summary().input,
7283                self.diff_transforms.items(()),
7284            );
7285        }
7286
7287        let mut prev_transform: Option<&DiffTransform> = None;
7288        for item in self.diff_transforms.iter() {
7289            if let DiffTransform::BufferContent {
7290                summary,
7291                inserted_hunk_info,
7292            } = item
7293            {
7294                if let Some(DiffTransform::BufferContent {
7295                    inserted_hunk_info: prev_inserted_hunk_info,
7296                    ..
7297                }) = prev_transform
7298                    && *inserted_hunk_info == *prev_inserted_hunk_info
7299                {
7300                    panic!(
7301                        "multiple adjacent buffer content transforms with is_inserted_hunk = {inserted_hunk_info:?}. transforms: {:+?}",
7302                        self.diff_transforms.items(())
7303                    );
7304                }
7305                if summary.len == MultiBufferOffset(0) && !self.is_empty() {
7306                    panic!("empty buffer content transform");
7307                }
7308            }
7309            prev_transform = Some(item);
7310        }
7311    }
7312}
7313
7314impl<'a, MBD, BD> MultiBufferCursor<'a, MBD, BD>
7315where
7316    MBD: MultiBufferDimension + Ord + Sub + ops::AddAssign<<MBD as Sub>::Output>,
7317    BD: TextDimension + AddAssign<<MBD as Sub>::Output>,
7318{
7319    #[instrument(skip_all)]
7320    fn seek(&mut self, position: &MBD) {
7321        let position = OutputDimension(*position);
7322        self.cached_region.take();
7323        self.diff_transforms.seek(&position, Bias::Right);
7324        if self.diff_transforms.item().is_none()
7325            && self.diff_transforms.start().output_dimension == position
7326        {
7327            self.diff_transforms.prev();
7328        }
7329
7330        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension;
7331        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7332            let overshoot = position - self.diff_transforms.start().output_dimension;
7333            excerpt_position += overshoot;
7334        }
7335
7336        self.excerpts.seek(&excerpt_position, Bias::Right);
7337        if self.excerpts.item().is_none() && excerpt_position == *self.excerpts.start() {
7338            self.excerpts.prev();
7339        }
7340    }
7341
7342    fn seek_forward(&mut self, position: &MBD) {
7343        let position = OutputDimension(*position);
7344        self.cached_region.take();
7345        self.diff_transforms.seek_forward(&position, Bias::Right);
7346        if self.diff_transforms.item().is_none()
7347            && self.diff_transforms.start().output_dimension == position
7348        {
7349            self.diff_transforms.prev();
7350        }
7351
7352        let overshoot = position - self.diff_transforms.start().output_dimension;
7353        let mut excerpt_position = self.diff_transforms.start().excerpt_dimension;
7354        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7355            excerpt_position += overshoot;
7356        }
7357
7358        self.excerpts.seek_forward(&excerpt_position, Bias::Right);
7359        if self.excerpts.item().is_none() && excerpt_position == *self.excerpts.start() {
7360            self.excerpts.prev();
7361        }
7362    }
7363
7364    fn next_excerpt(&mut self) {
7365        self.excerpts.next();
7366        self.seek_to_start_of_current_excerpt();
7367    }
7368
7369    fn prev_excerpt(&mut self) {
7370        self.excerpts.prev();
7371        self.seek_to_start_of_current_excerpt();
7372    }
7373
7374    fn seek_to_start_of_current_excerpt(&mut self) {
7375        self.cached_region.take();
7376
7377        if self.diff_transforms.seek(self.excerpts.start(), Bias::Left)
7378            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
7379            && self.diff_transforms.next_item().is_some()
7380        {
7381            self.diff_transforms.next();
7382        }
7383    }
7384
7385    fn next_excerpt_forwards(&mut self) {
7386        self.excerpts.next();
7387        self.seek_to_start_of_current_excerpt_forward();
7388    }
7389
7390    fn seek_to_start_of_current_excerpt_forward(&mut self) {
7391        self.cached_region.take();
7392
7393        if self
7394            .diff_transforms
7395            .seek_forward(self.excerpts.start(), Bias::Left)
7396            && self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
7397            && self.diff_transforms.next_item().is_some()
7398        {
7399            self.diff_transforms.next();
7400        }
7401    }
7402
7403    fn next(&mut self) {
7404        self.cached_region.take();
7405        match self
7406            .diff_transforms
7407            .end()
7408            .excerpt_dimension
7409            .cmp(&self.excerpts.end())
7410        {
7411            cmp::Ordering::Less => self.diff_transforms.next(),
7412            cmp::Ordering::Greater => self.excerpts.next(),
7413            cmp::Ordering::Equal => {
7414                self.diff_transforms.next();
7415                if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
7416                    || self.diff_transforms.item().is_none()
7417                {
7418                    self.excerpts.next();
7419                } else if let Some(DiffTransform::DeletedHunk { hunk_info, .. }) =
7420                    self.diff_transforms.item()
7421                    && self
7422                        .excerpts
7423                        .item()
7424                        .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id)
7425                {
7426                    self.excerpts.next();
7427                }
7428            }
7429        }
7430    }
7431
7432    fn prev(&mut self) {
7433        self.cached_region.take();
7434        match self
7435            .diff_transforms
7436            .start()
7437            .excerpt_dimension
7438            .cmp(self.excerpts.start())
7439        {
7440            cmp::Ordering::Less => self.excerpts.prev(),
7441            cmp::Ordering::Greater => self.diff_transforms.prev(),
7442            cmp::Ordering::Equal => {
7443                self.diff_transforms.prev();
7444                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start()
7445                    || self.diff_transforms.item().is_none()
7446                {
7447                    self.excerpts.prev();
7448                }
7449            }
7450        }
7451    }
7452
7453    fn region(&self) -> Option<&MultiBufferRegion<'a, MBD, BD>> {
7454        self.cached_region
7455            .get_or_init(|| self.build_region())
7456            .as_ref()
7457    }
7458
7459    fn is_at_start_of_excerpt(&mut self) -> bool {
7460        if self.diff_transforms.start().excerpt_dimension > *self.excerpts.start() {
7461            return false;
7462        } else if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
7463            return true;
7464        }
7465
7466        self.diff_transforms.prev();
7467        let prev_transform = self.diff_transforms.item();
7468        self.diff_transforms.next();
7469
7470        prev_transform.is_none_or(|next_transform| {
7471            matches!(next_transform, DiffTransform::BufferContent { .. })
7472        })
7473    }
7474
7475    fn is_at_end_of_excerpt(&self) -> bool {
7476        if self.diff_transforms.end().excerpt_dimension < self.excerpts.end() {
7477            return false;
7478        } else if self.diff_transforms.end().excerpt_dimension > self.excerpts.end()
7479            || self.diff_transforms.item().is_none()
7480        {
7481            return true;
7482        }
7483
7484        let next_transform = self.diff_transforms.next_item();
7485        next_transform.is_none_or(|next_transform| match next_transform {
7486            DiffTransform::BufferContent { .. } => true,
7487            DiffTransform::DeletedHunk { hunk_info, .. } => self
7488                .excerpts
7489                .item()
7490                .is_some_and(|excerpt| excerpt.id != hunk_info.excerpt_id),
7491        })
7492    }
7493
7494    fn main_buffer_position(&self) -> Option<BD> {
7495        let excerpt = self.excerpts.item()?;
7496        let buffer = &excerpt.buffer;
7497        let buffer_context_start = excerpt.range.context.start.summary::<BD>(buffer);
7498        let mut buffer_start = buffer_context_start;
7499        let overshoot = self.diff_transforms.end().excerpt_dimension - *self.excerpts.start();
7500        buffer_start += overshoot;
7501        Some(buffer_start)
7502    }
7503
7504    fn build_region(&self) -> Option<MultiBufferRegion<'a, MBD, BD>> {
7505        let excerpt = self.excerpts.item()?;
7506        match self.diff_transforms.item()? {
7507            DiffTransform::DeletedHunk {
7508                buffer_id,
7509                base_text_byte_range,
7510                has_trailing_newline,
7511                hunk_info,
7512                ..
7513            } => {
7514                let diff = self.diffs.get(buffer_id)?;
7515                let buffer = diff.base_text();
7516                let mut rope_cursor = buffer.as_rope().cursor(0);
7517                let buffer_start = rope_cursor.summary::<BD>(base_text_byte_range.start);
7518                let buffer_range_len = rope_cursor.summary::<BD>(base_text_byte_range.end);
7519                let mut buffer_end = buffer_start;
7520                TextDimension::add_assign(&mut buffer_end, &buffer_range_len);
7521                let start = self.diff_transforms.start().output_dimension.0;
7522                let end = self.diff_transforms.end().output_dimension.0;
7523                Some(MultiBufferRegion {
7524                    buffer,
7525                    excerpt,
7526                    has_trailing_newline: *has_trailing_newline,
7527                    is_main_buffer: false,
7528                    diff_hunk_status: Some(DiffHunkStatus::deleted(
7529                        hunk_info.hunk_secondary_status,
7530                    )),
7531                    buffer_range: buffer_start..buffer_end,
7532                    range: start..end,
7533                })
7534            }
7535            DiffTransform::BufferContent {
7536                inserted_hunk_info, ..
7537            } => {
7538                let buffer = &excerpt.buffer;
7539                let buffer_context_start = excerpt.range.context.start.summary::<BD>(buffer);
7540
7541                let mut start = self.diff_transforms.start().output_dimension.0;
7542                let mut buffer_start = buffer_context_start;
7543                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
7544                    let overshoot =
7545                        *self.excerpts.start() - self.diff_transforms.start().excerpt_dimension;
7546                    start += overshoot;
7547                } else {
7548                    let overshoot =
7549                        self.diff_transforms.start().excerpt_dimension - *self.excerpts.start();
7550                    buffer_start += overshoot;
7551                }
7552
7553                let mut end;
7554                let mut buffer_end;
7555                let has_trailing_newline;
7556                let transform_end = self.diff_transforms.end();
7557                if transform_end.excerpt_dimension < self.excerpts.end() {
7558                    let overshoot = transform_end.excerpt_dimension - *self.excerpts.start();
7559                    end = transform_end.output_dimension.0;
7560                    buffer_end = buffer_context_start;
7561                    buffer_end += overshoot;
7562                    has_trailing_newline = false;
7563                } else {
7564                    let overshoot =
7565                        self.excerpts.end() - self.diff_transforms.start().excerpt_dimension;
7566                    end = self.diff_transforms.start().output_dimension.0;
7567                    end += overshoot;
7568                    buffer_end = excerpt.range.context.end.summary::<BD>(buffer);
7569                    has_trailing_newline = excerpt.has_trailing_newline;
7570                };
7571
7572                let diff_hunk_status = inserted_hunk_info.map(|info| {
7573                    if info.is_logically_deleted {
7574                        DiffHunkStatus::deleted(info.hunk_secondary_status)
7575                    } else {
7576                        DiffHunkStatus::added(info.hunk_secondary_status)
7577                    }
7578                });
7579
7580                Some(MultiBufferRegion {
7581                    buffer,
7582                    excerpt,
7583                    has_trailing_newline,
7584                    is_main_buffer: true,
7585                    diff_hunk_status,
7586                    buffer_range: buffer_start..buffer_end,
7587                    range: start..end,
7588                })
7589            }
7590        }
7591    }
7592
7593    fn fetch_excerpt_with_range(&self) -> Option<(&'a Excerpt, Range<MBD>)> {
7594        let excerpt = self.excerpts.item()?;
7595        match self.diff_transforms.item()? {
7596            &DiffTransform::DeletedHunk { .. } => {
7597                let start = self.diff_transforms.start().output_dimension.0;
7598                let end = self.diff_transforms.end().output_dimension.0;
7599                Some((excerpt, start..end))
7600            }
7601            DiffTransform::BufferContent { .. } => {
7602                let mut start = self.diff_transforms.start().output_dimension.0;
7603                if self.diff_transforms.start().excerpt_dimension < *self.excerpts.start() {
7604                    let overshoot =
7605                        *self.excerpts.start() - self.diff_transforms.start().excerpt_dimension;
7606                    start += overshoot;
7607                }
7608
7609                let mut end;
7610                let transform_end = self.diff_transforms.end();
7611                if transform_end.excerpt_dimension < self.excerpts.end() {
7612                    end = transform_end.output_dimension.0;
7613                } else {
7614                    let overshoot =
7615                        self.excerpts.end() - self.diff_transforms.start().excerpt_dimension;
7616                    end = self.diff_transforms.start().output_dimension.0;
7617                    end += overshoot;
7618                };
7619
7620                Some((excerpt, start..end))
7621            }
7622        }
7623    }
7624
7625    fn excerpt(&self) -> Option<&'a Excerpt> {
7626        self.excerpts.item()
7627    }
7628}
7629
7630impl Excerpt {
7631    fn new(
7632        id: ExcerptId,
7633        locator: Locator,
7634        buffer_id: BufferId,
7635        buffer: Arc<BufferSnapshot>,
7636        range: ExcerptRange<text::Anchor>,
7637        has_trailing_newline: bool,
7638    ) -> Self {
7639        Excerpt {
7640            id,
7641            locator,
7642            max_buffer_row: range.context.end.to_point(&buffer).row,
7643            text_summary: buffer
7644                .text_summary_for_range::<TextSummary, _>(range.context.to_offset(&buffer)),
7645            buffer_id,
7646            buffer,
7647            range,
7648            has_trailing_newline,
7649        }
7650    }
7651
7652    fn chunks_in_range(&self, range: Range<usize>, language_aware: bool) -> ExcerptChunks<'_> {
7653        let content_start = self.range.context.start.to_offset(&self.buffer);
7654        let chunks_start = content_start + range.start;
7655        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
7656
7657        let has_footer = self.has_trailing_newline
7658            && range.start <= self.text_summary.len
7659            && range.end > self.text_summary.len;
7660
7661        let content_chunks = self.buffer.chunks(chunks_start..chunks_end, language_aware);
7662
7663        ExcerptChunks {
7664            excerpt_id: self.id,
7665            content_chunks,
7666            has_footer,
7667        }
7668    }
7669
7670    fn seek_chunks(&self, excerpt_chunks: &mut ExcerptChunks, range: Range<usize>) {
7671        let content_start = self.range.context.start.to_offset(&self.buffer);
7672        let chunks_start = content_start + range.start;
7673        let chunks_end = content_start + cmp::min(range.end, self.text_summary.len);
7674        excerpt_chunks.content_chunks.seek(chunks_start..chunks_end);
7675        excerpt_chunks.has_footer = self.has_trailing_newline
7676            && range.start <= self.text_summary.len
7677            && range.end > self.text_summary.len;
7678    }
7679
7680    fn clip_anchor(&self, text_anchor: text::Anchor) -> text::Anchor {
7681        if text_anchor
7682            .cmp(&self.range.context.start, &self.buffer)
7683            .is_lt()
7684        {
7685            self.range.context.start
7686        } else if text_anchor
7687            .cmp(&self.range.context.end, &self.buffer)
7688            .is_gt()
7689        {
7690            self.range.context.end
7691        } else {
7692            text_anchor
7693        }
7694    }
7695
7696    fn contains(&self, anchor: &Anchor) -> bool {
7697        (anchor.text_anchor.buffer_id == None
7698            || anchor.text_anchor.buffer_id == Some(self.buffer_id))
7699            && self
7700                .range
7701                .context
7702                .start
7703                .cmp(&anchor.text_anchor, &self.buffer)
7704                .is_le()
7705            && self
7706                .range
7707                .context
7708                .end
7709                .cmp(&anchor.text_anchor, &self.buffer)
7710                .is_ge()
7711    }
7712
7713    /// The [`Excerpt`]'s start offset in its [`Buffer`]
7714    fn buffer_start_offset(&self) -> BufferOffset {
7715        BufferOffset(self.range.context.start.to_offset(&self.buffer))
7716    }
7717
7718    /// The [`Excerpt`]'s end offset in its [`Buffer`]
7719    fn buffer_end_offset(&self) -> BufferOffset {
7720        self.buffer_start_offset() + self.text_summary.len
7721    }
7722}
7723
7724impl<'a> MultiBufferExcerpt<'a> {
7725    pub fn id(&self) -> ExcerptId {
7726        self.excerpt.id
7727    }
7728
7729    pub fn buffer_id(&self) -> BufferId {
7730        self.excerpt.buffer_id
7731    }
7732
7733    pub fn start_anchor(&self) -> Anchor {
7734        Anchor::in_buffer(self.excerpt.id, self.excerpt.range.context.start)
7735    }
7736
7737    pub fn end_anchor(&self) -> Anchor {
7738        Anchor::in_buffer(self.excerpt.id, self.excerpt.range.context.end)
7739    }
7740
7741    pub fn buffer(&self) -> &'a BufferSnapshot {
7742        &self.excerpt.buffer
7743    }
7744
7745    pub fn buffer_range(&self) -> Range<BufferOffset> {
7746        self.buffer_offset
7747            ..BufferOffset(
7748                self.excerpt
7749                    .range
7750                    .context
7751                    .end
7752                    .to_offset(&self.excerpt.buffer.text),
7753            )
7754    }
7755
7756    pub fn start_offset(&self) -> MultiBufferOffset {
7757        self.offset
7758    }
7759
7760    /// Maps an offset within the [`MultiBuffer`] to an offset within the [`Buffer`]
7761    pub fn map_offset_to_buffer(&mut self, offset: MultiBufferOffset) -> BufferOffset {
7762        self.map_range_to_buffer(offset..offset).start
7763    }
7764
7765    /// Maps a range within the [`MultiBuffer`] to a range within the [`Buffer`]
7766    pub fn map_range_to_buffer(&mut self, range: Range<MultiBufferOffset>) -> Range<BufferOffset> {
7767        self.diff_transforms
7768            .seek(&OutputDimension(range.start), Bias::Right);
7769        let start = self.map_offset_to_buffer_internal(range.start);
7770        let end = if range.end > range.start {
7771            self.diff_transforms
7772                .seek_forward(&OutputDimension(range.end), Bias::Right);
7773            self.map_offset_to_buffer_internal(range.end)
7774        } else {
7775            start
7776        };
7777        start..end
7778    }
7779
7780    fn map_offset_to_buffer_internal(&self, offset: MultiBufferOffset) -> BufferOffset {
7781        let mut excerpt_offset = self.diff_transforms.start().excerpt_dimension;
7782        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
7783            excerpt_offset += offset - self.diff_transforms.start().output_dimension.0;
7784        };
7785        let offset_in_excerpt = excerpt_offset.saturating_sub(self.excerpt_offset);
7786        self.buffer_offset + offset_in_excerpt
7787    }
7788
7789    /// Map an offset within the [`Buffer`] to an offset within the [`MultiBuffer`]
7790    pub fn map_offset_from_buffer(&mut self, buffer_offset: BufferOffset) -> MultiBufferOffset {
7791        self.map_range_from_buffer(buffer_offset..buffer_offset)
7792            .start
7793    }
7794
7795    /// Map a range within the [`Buffer`] to a range within the [`MultiBuffer`]
7796    pub fn map_range_from_buffer(
7797        &mut self,
7798        buffer_range: Range<BufferOffset>,
7799    ) -> Range<MultiBufferOffset> {
7800        if buffer_range.start < self.buffer_offset {
7801            log::warn!(
7802                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7803            );
7804            return self.offset..self.offset;
7805        }
7806        let overshoot = buffer_range.start - self.buffer_offset;
7807        let excerpt_offset = self.excerpt_offset + overshoot;
7808        let excerpt_seek_dim = excerpt_offset;
7809        self.diff_transforms.seek(&excerpt_seek_dim, Bias::Right);
7810        if self.diff_transforms.start().excerpt_dimension > excerpt_offset {
7811            log::warn!(
7812                "Attempting to map a range from a buffer offset that starts before the current buffer offset"
7813            );
7814            return self.offset..self.offset;
7815        }
7816        let overshoot = excerpt_offset - self.diff_transforms.start().excerpt_dimension;
7817        let start = self.diff_transforms.start().output_dimension.0 + overshoot;
7818
7819        let end = if buffer_range.start < buffer_range.end {
7820            let overshoot = buffer_range.end - self.buffer_offset;
7821            let excerpt_offset = self.excerpt_offset + overshoot;
7822            let excerpt_seek_dim = excerpt_offset;
7823            self.diff_transforms
7824                .seek_forward(&excerpt_seek_dim, Bias::Right);
7825            let overshoot = excerpt_offset - self.diff_transforms.start().excerpt_dimension;
7826            // todo(lw): Clamp end to the excerpt boundaries
7827            self.diff_transforms.start().output_dimension.0 + overshoot
7828        } else {
7829            start
7830        };
7831
7832        start..end
7833    }
7834
7835    /// Returns true if the entirety of the given range is in the buffer's excerpt
7836    pub fn contains_buffer_range(&self, range: Range<BufferOffset>) -> bool {
7837        range.start >= self.excerpt.buffer_start_offset()
7838            && range.end <= self.excerpt.buffer_end_offset()
7839    }
7840
7841    /// Returns true if any part of the given range is in the buffer's excerpt
7842    pub fn contains_partial_buffer_range(&self, range: Range<BufferOffset>) -> bool {
7843        range.start <= self.excerpt.buffer_end_offset()
7844            && range.end >= self.excerpt.buffer_start_offset()
7845    }
7846
7847    pub fn max_buffer_row(&self) -> u32 {
7848        self.excerpt.max_buffer_row
7849    }
7850}
7851
7852impl ExcerptId {
7853    pub fn min() -> Self {
7854        Self(0)
7855    }
7856
7857    pub fn max() -> Self {
7858        Self(u32::MAX)
7859    }
7860
7861    pub fn to_proto(self) -> u64 {
7862        self.0 as _
7863    }
7864
7865    pub fn from_proto(proto: u64) -> Self {
7866        Self(proto as _)
7867    }
7868
7869    pub fn cmp(&self, other: &Self, snapshot: &MultiBufferSnapshot) -> cmp::Ordering {
7870        let a = snapshot.excerpt_locator_for_id(*self);
7871        let b = snapshot.excerpt_locator_for_id(*other);
7872        a.cmp(b).then_with(|| self.0.cmp(&other.0))
7873    }
7874}
7875
7876impl From<ExcerptId> for usize {
7877    fn from(val: ExcerptId) -> Self {
7878        val.0 as usize
7879    }
7880}
7881
7882impl fmt::Debug for Excerpt {
7883    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
7884        f.debug_struct("Excerpt")
7885            .field("id", &self.id)
7886            .field("locator", &self.locator)
7887            .field("buffer_id", &self.buffer_id)
7888            .field("range", &self.range)
7889            .field("text_summary", &self.text_summary)
7890            .field("has_trailing_newline", &self.has_trailing_newline)
7891            .finish()
7892    }
7893}
7894
7895impl sum_tree::Item for Excerpt {
7896    type Summary = ExcerptSummary;
7897
7898    fn summary(&self, _cx: ()) -> Self::Summary {
7899        let mut text = self.text_summary;
7900        if self.has_trailing_newline {
7901            text += TextSummary::from("\n");
7902        }
7903        ExcerptSummary {
7904            excerpt_id: self.id,
7905            excerpt_locator: self.locator.clone(),
7906            widest_line_number: self.max_buffer_row,
7907            text: text.into(),
7908            count: 1,
7909        }
7910    }
7911}
7912
7913impl sum_tree::Item for ExcerptIdMapping {
7914    type Summary = ExcerptId;
7915
7916    fn summary(&self, _cx: ()) -> Self::Summary {
7917        self.id
7918    }
7919}
7920
7921impl sum_tree::KeyedItem for ExcerptIdMapping {
7922    type Key = ExcerptId;
7923
7924    fn key(&self) -> Self::Key {
7925        self.id
7926    }
7927}
7928
7929impl DiffTransform {
7930    fn hunk_info(&self) -> Option<DiffTransformHunkInfo> {
7931        match self {
7932            DiffTransform::DeletedHunk { hunk_info, .. } => Some(*hunk_info),
7933            DiffTransform::BufferContent {
7934                inserted_hunk_info, ..
7935            } => *inserted_hunk_info,
7936        }
7937    }
7938}
7939
7940impl sum_tree::Item for DiffTransform {
7941    type Summary = DiffTransformSummary;
7942
7943    fn summary(&self, _: <Self::Summary as sum_tree::Summary>::Context<'_>) -> Self::Summary {
7944        match self {
7945            DiffTransform::BufferContent { summary, .. } => DiffTransformSummary {
7946                input: *summary,
7947                output: *summary,
7948            },
7949            &DiffTransform::DeletedHunk { summary, .. } => DiffTransformSummary {
7950                input: MBTextSummary::default(),
7951                output: summary.into(),
7952            },
7953        }
7954    }
7955}
7956
7957impl DiffTransformSummary {
7958    fn excerpt_len(&self) -> ExcerptOffset {
7959        ExcerptDimension(self.input.len)
7960    }
7961}
7962
7963impl sum_tree::ContextLessSummary for DiffTransformSummary {
7964    fn zero() -> Self {
7965        DiffTransformSummary {
7966            input: MBTextSummary::default(),
7967            output: MBTextSummary::default(),
7968        }
7969    }
7970
7971    fn add_summary(&mut self, other: &Self) {
7972        self.input += other.input;
7973        self.output += other.output;
7974    }
7975}
7976
7977impl sum_tree::ContextLessSummary for ExcerptId {
7978    fn zero() -> Self {
7979        Self(0)
7980    }
7981
7982    fn add_summary(&mut self, summary: &Self) {
7983        *self = cmp::max(*self, *summary);
7984    }
7985}
7986
7987impl sum_tree::ContextLessSummary for ExcerptSummary {
7988    fn zero() -> Self {
7989        Self::default()
7990    }
7991
7992    fn add_summary(&mut self, summary: &Self) {
7993        debug_assert!(
7994            summary.excerpt_locator > self.excerpt_locator
7995                || self.excerpt_locator == Locator::min(),
7996            "Excerpt locators must be in ascending order: {:?} > {:?}",
7997            summary.excerpt_locator,
7998            self.excerpt_locator
7999        );
8000        self.excerpt_locator = summary.excerpt_locator.clone();
8001        self.text += summary.text;
8002        self.widest_line_number = cmp::max(self.widest_line_number, summary.widest_line_number);
8003        self.count += summary.count;
8004    }
8005}
8006
8007impl<'a> sum_tree::SeekTarget<'a, ExcerptSummary, Option<&'a Locator>> for Locator {
8008    fn cmp(&self, cursor_location: &Option<&'a Locator>, _: ()) -> cmp::Ordering {
8009        Ord::cmp(&Some(self), cursor_location)
8010    }
8011}
8012
8013impl sum_tree::SeekTarget<'_, ExcerptSummary, ExcerptSummary> for Locator {
8014    fn cmp(&self, cursor_location: &ExcerptSummary, _: ()) -> cmp::Ordering {
8015        Ord::cmp(self, &cursor_location.excerpt_locator)
8016    }
8017}
8018
8019impl<'a, MBD> sum_tree::Dimension<'a, ExcerptSummary> for ExcerptDimension<MBD>
8020where
8021    MBD: MultiBufferDimension + Default,
8022{
8023    fn zero(_: ()) -> Self {
8024        ExcerptDimension(MBD::default())
8025    }
8026
8027    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
8028        MultiBufferDimension::add_mb_text_summary(&mut self.0, &summary.text)
8029    }
8030}
8031
8032impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<&'a Locator> {
8033    fn zero(_cx: ()) -> Self {
8034        Default::default()
8035    }
8036
8037    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
8038        *self = Some(&summary.excerpt_locator);
8039    }
8040}
8041
8042impl<'a> sum_tree::Dimension<'a, ExcerptSummary> for Option<ExcerptId> {
8043    fn zero(_cx: ()) -> Self {
8044        Default::default()
8045    }
8046
8047    fn add_summary(&mut self, summary: &'a ExcerptSummary, _: ()) {
8048        *self = Some(summary.excerpt_id);
8049    }
8050}
8051
8052#[derive(Copy, Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
8053struct OutputDimension<T>(T);
8054
8055impl<T: PartialEq> PartialEq<T> for OutputDimension<T> {
8056    fn eq(&self, other: &T) -> bool {
8057        self.0 == *other
8058    }
8059}
8060
8061impl<T: PartialOrd> PartialOrd<T> for OutputDimension<T> {
8062    fn partial_cmp(&self, other: &T) -> Option<cmp::Ordering> {
8063        self.0.partial_cmp(other)
8064    }
8065}
8066
8067impl<R, T, U> ops::Sub<OutputDimension<U>> for OutputDimension<T>
8068where
8069    T: ops::Sub<U, Output = R>,
8070{
8071    type Output = R;
8072
8073    fn sub(self, other: OutputDimension<U>) -> Self::Output {
8074        self.0 - other.0
8075    }
8076}
8077
8078impl<R, T, U> ops::Add<U> for OutputDimension<T>
8079where
8080    T: ops::Add<U, Output = R>,
8081{
8082    type Output = OutputDimension<R>;
8083
8084    fn add(self, other: U) -> Self::Output {
8085        OutputDimension(self.0 + other)
8086    }
8087}
8088
8089impl<T, U> AddAssign<U> for OutputDimension<T>
8090where
8091    T: AddAssign<U>,
8092{
8093    fn add_assign(&mut self, other: U) {
8094        self.0 += other;
8095    }
8096}
8097
8098impl<T, U> SubAssign<U> for OutputDimension<T>
8099where
8100    T: SubAssign<U>,
8101{
8102    fn sub_assign(&mut self, other: U) {
8103        self.0 -= other;
8104    }
8105}
8106
8107#[derive(Copy, Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
8108struct ExcerptDimension<T>(T);
8109
8110impl<T: PartialEq> PartialEq<T> for ExcerptDimension<T> {
8111    fn eq(&self, other: &T) -> bool {
8112        self.0 == *other
8113    }
8114}
8115
8116impl<T: PartialOrd> PartialOrd<T> for ExcerptDimension<T> {
8117    fn partial_cmp(&self, other: &T) -> Option<cmp::Ordering> {
8118        self.0.partial_cmp(other)
8119    }
8120}
8121
8122impl ExcerptOffset {
8123    fn saturating_sub(self, other: ExcerptOffset) -> usize {
8124        self.0.saturating_sub(other.0)
8125    }
8126}
8127
8128impl<R, T, U> ops::Sub<ExcerptDimension<U>> for ExcerptDimension<T>
8129where
8130    T: ops::Sub<U, Output = R>,
8131{
8132    type Output = R;
8133
8134    fn sub(self, other: ExcerptDimension<U>) -> Self::Output {
8135        self.0 - other.0
8136    }
8137}
8138
8139impl<R, T, U> ops::Add<U> for ExcerptDimension<T>
8140where
8141    T: ops::Add<U, Output = R>,
8142{
8143    type Output = ExcerptDimension<R>;
8144
8145    fn add(self, other: U) -> Self::Output {
8146        ExcerptDimension(self.0 + other)
8147    }
8148}
8149
8150impl<T, U> AddAssign<U> for ExcerptDimension<T>
8151where
8152    T: AddAssign<U>,
8153{
8154    fn add_assign(&mut self, other: U) {
8155        self.0 += other;
8156    }
8157}
8158
8159impl<T, U> SubAssign<U> for ExcerptDimension<T>
8160where
8161    T: SubAssign<U>,
8162{
8163    fn sub_assign(&mut self, other: U) {
8164        self.0 -= other;
8165    }
8166}
8167
8168impl<'a> sum_tree::Dimension<'a, DiffTransformSummary> for MultiBufferOffset {
8169    fn zero(_: ()) -> Self {
8170        MultiBufferOffset::ZERO
8171    }
8172
8173    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
8174        *self += summary.output.len;
8175    }
8176}
8177
8178impl<MBD> sum_tree::SeekTarget<'_, DiffTransformSummary, DiffTransformSummary>
8179    for ExcerptDimension<MBD>
8180where
8181    MBD: MultiBufferDimension + Ord,
8182{
8183    fn cmp(&self, cursor_location: &DiffTransformSummary, _: ()) -> cmp::Ordering {
8184        Ord::cmp(&self.0, &MBD::from_summary(&cursor_location.input))
8185    }
8186}
8187
8188impl<'a, MBD> sum_tree::SeekTarget<'a, DiffTransformSummary, DiffTransforms<MBD>>
8189    for ExcerptDimension<MBD>
8190where
8191    MBD: MultiBufferDimension + Ord,
8192{
8193    fn cmp(&self, cursor_location: &DiffTransforms<MBD>, _: ()) -> cmp::Ordering {
8194        Ord::cmp(&self.0, &cursor_location.excerpt_dimension.0)
8195    }
8196}
8197
8198impl<'a, MBD: MultiBufferDimension> sum_tree::Dimension<'a, DiffTransformSummary>
8199    for ExcerptDimension<MBD>
8200{
8201    fn zero(_: ()) -> Self {
8202        ExcerptDimension(MBD::default())
8203    }
8204
8205    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
8206        self.0.add_mb_text_summary(&summary.input)
8207    }
8208}
8209
8210impl<'a, MBD> sum_tree::SeekTarget<'a, DiffTransformSummary, DiffTransforms<MBD>>
8211    for OutputDimension<MBD>
8212where
8213    MBD: MultiBufferDimension + Ord,
8214{
8215    fn cmp(&self, cursor_location: &DiffTransforms<MBD>, _: ()) -> cmp::Ordering {
8216        Ord::cmp(&self.0, &cursor_location.output_dimension.0)
8217    }
8218}
8219
8220impl<'a, MBD: MultiBufferDimension> sum_tree::Dimension<'a, DiffTransformSummary>
8221    for OutputDimension<MBD>
8222{
8223    fn zero(_: ()) -> Self {
8224        OutputDimension(MBD::default())
8225    }
8226
8227    fn add_summary(&mut self, summary: &'a DiffTransformSummary, _: ()) {
8228        self.0.add_mb_text_summary(&summary.output)
8229    }
8230}
8231
8232impl MultiBufferRows<'_> {
8233    pub fn seek(&mut self, MultiBufferRow(row): MultiBufferRow) {
8234        self.point = Point::new(row, 0);
8235        self.cursor.seek(&self.point);
8236    }
8237}
8238
8239impl Iterator for MultiBufferRows<'_> {
8240    type Item = RowInfo;
8241
8242    fn next(&mut self) -> Option<Self::Item> {
8243        if self.is_empty && self.point.row == 0 {
8244            self.point += Point::new(1, 0);
8245            return Some(RowInfo {
8246                buffer_id: None,
8247                buffer_row: Some(0),
8248                multibuffer_row: Some(MultiBufferRow(0)),
8249                diff_status: None,
8250                expand_info: None,
8251                wrapped_buffer_row: None,
8252            });
8253        }
8254
8255        let mut region = self.cursor.region()?.clone();
8256        while self.point >= region.range.end {
8257            self.cursor.next();
8258            if let Some(next_region) = self.cursor.region() {
8259                region = next_region.clone();
8260            } else if self.point == self.cursor.diff_transforms.end().output_dimension.0 {
8261                let multibuffer_row = MultiBufferRow(self.point.row);
8262                let last_excerpt = self
8263                    .cursor
8264                    .excerpts
8265                    .item()
8266                    .or(self.cursor.excerpts.prev_item())?;
8267                let last_row = last_excerpt
8268                    .range
8269                    .context
8270                    .end
8271                    .to_point(&last_excerpt.buffer)
8272                    .row;
8273
8274                let first_row = last_excerpt
8275                    .range
8276                    .context
8277                    .start
8278                    .to_point(&last_excerpt.buffer)
8279                    .row;
8280
8281                let expand_info = if self.is_singleton {
8282                    None
8283                } else {
8284                    let needs_expand_up = first_row == last_row
8285                        && last_row > 0
8286                        && !region.diff_hunk_status.is_some_and(|d| d.is_deleted());
8287                    let needs_expand_down = last_row < last_excerpt.buffer.max_point().row;
8288
8289                    if needs_expand_up && needs_expand_down {
8290                        Some(ExpandExcerptDirection::UpAndDown)
8291                    } else if needs_expand_up {
8292                        Some(ExpandExcerptDirection::Up)
8293                    } else if needs_expand_down {
8294                        Some(ExpandExcerptDirection::Down)
8295                    } else {
8296                        None
8297                    }
8298                    .map(|direction| ExpandInfo {
8299                        direction,
8300                        excerpt_id: last_excerpt.id,
8301                    })
8302                };
8303                self.point += Point::new(1, 0);
8304                return Some(RowInfo {
8305                    buffer_id: Some(last_excerpt.buffer_id),
8306                    buffer_row: Some(last_row),
8307                    multibuffer_row: Some(multibuffer_row),
8308                    diff_status: None,
8309                    wrapped_buffer_row: None,
8310                    expand_info,
8311                });
8312            } else {
8313                return None;
8314            };
8315        }
8316
8317        let overshoot = self.point - region.range.start;
8318        let buffer_point = region.buffer_range.start + overshoot;
8319        let expand_info = if self.is_singleton {
8320            None
8321        } else {
8322            let needs_expand_up = self.point.row == region.range.start.row
8323                && self.cursor.is_at_start_of_excerpt()
8324                && buffer_point.row > 0;
8325            let needs_expand_down = (region.excerpt.has_trailing_newline
8326                && self.point.row + 1 == region.range.end.row
8327                || !region.excerpt.has_trailing_newline && self.point.row == region.range.end.row)
8328                && self.cursor.is_at_end_of_excerpt()
8329                && buffer_point.row < region.buffer.max_point().row;
8330
8331            if needs_expand_up && needs_expand_down {
8332                Some(ExpandExcerptDirection::UpAndDown)
8333            } else if needs_expand_up {
8334                Some(ExpandExcerptDirection::Up)
8335            } else if needs_expand_down {
8336                Some(ExpandExcerptDirection::Down)
8337            } else {
8338                None
8339            }
8340            .map(|direction| ExpandInfo {
8341                direction,
8342                excerpt_id: region.excerpt.id,
8343            })
8344        };
8345
8346        let result = Some(RowInfo {
8347            buffer_id: Some(region.buffer.remote_id()),
8348            buffer_row: Some(buffer_point.row),
8349            multibuffer_row: Some(MultiBufferRow(self.point.row)),
8350            diff_status: region
8351                .diff_hunk_status
8352                .filter(|_| self.point < region.range.end),
8353            expand_info,
8354            wrapped_buffer_row: None,
8355        });
8356        self.point += Point::new(1, 0);
8357        result
8358    }
8359}
8360
8361impl<'a> MultiBufferChunks<'a> {
8362    pub fn offset(&self) -> MultiBufferOffset {
8363        self.range.start
8364    }
8365
8366    pub fn seek(&mut self, range: Range<MultiBufferOffset>) {
8367        self.diff_transforms.seek(&range.end, Bias::Right);
8368        let mut excerpt_end = self.diff_transforms.start().1;
8369        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
8370            let overshoot = range.end - self.diff_transforms.start().0;
8371            excerpt_end += overshoot;
8372        }
8373
8374        self.diff_transforms.seek(&range.start, Bias::Right);
8375        let mut excerpt_start = self.diff_transforms.start().1;
8376        if let Some(DiffTransform::BufferContent { .. }) = self.diff_transforms.item() {
8377            let overshoot = range.start - self.diff_transforms.start().0;
8378            excerpt_start += overshoot;
8379        }
8380
8381        self.seek_to_excerpt_offset_range(excerpt_start..excerpt_end);
8382        self.buffer_chunk.take();
8383        self.range = range;
8384    }
8385
8386    fn seek_to_excerpt_offset_range(&mut self, new_range: Range<ExcerptOffset>) {
8387        self.excerpt_offset_range = new_range.clone();
8388        self.excerpts.seek(&new_range.start, Bias::Right);
8389        if let Some(excerpt) = self.excerpts.item() {
8390            let excerpt_start = *self.excerpts.start();
8391            if let Some(excerpt_chunks) = self
8392                .excerpt_chunks
8393                .as_mut()
8394                .filter(|chunks| excerpt.id == chunks.excerpt_id)
8395            {
8396                excerpt.seek_chunks(
8397                    excerpt_chunks,
8398                    (self.excerpt_offset_range.start - excerpt_start)
8399                        ..(self.excerpt_offset_range.end - excerpt_start),
8400                );
8401            } else {
8402                self.excerpt_chunks = Some(excerpt.chunks_in_range(
8403                    (self.excerpt_offset_range.start - excerpt_start)
8404                        ..(self.excerpt_offset_range.end - excerpt_start),
8405                    self.language_aware,
8406                ));
8407            }
8408        } else {
8409            self.excerpt_chunks = None;
8410        }
8411    }
8412
8413    #[ztracing::instrument(skip_all)]
8414    fn next_excerpt_chunk(&mut self) -> Option<Chunk<'a>> {
8415        loop {
8416            if self.excerpt_offset_range.is_empty() {
8417                return None;
8418            } else if let Some(chunk) = self.excerpt_chunks.as_mut()?.next() {
8419                self.excerpt_offset_range.start += chunk.text.len();
8420                return Some(chunk);
8421            } else {
8422                self.excerpts.next();
8423                let excerpt = self.excerpts.item()?;
8424                self.excerpt_chunks = Some(excerpt.chunks_in_range(
8425                    0..(self.excerpt_offset_range.end - *self.excerpts.start()),
8426                    self.language_aware,
8427                ));
8428            }
8429        }
8430    }
8431}
8432
8433impl<'a> Iterator for ReversedMultiBufferChunks<'a> {
8434    type Item = &'a str;
8435
8436    fn next(&mut self) -> Option<Self::Item> {
8437        let mut region = self.cursor.region()?;
8438        if self.offset == region.range.start {
8439            self.cursor.prev();
8440            region = self.cursor.region()?;
8441            let start_overshoot = self.start.saturating_sub(region.range.start);
8442            self.current_chunks = Some(region.buffer.reversed_chunks_in_range(
8443                region.buffer_range.start + start_overshoot..region.buffer_range.end,
8444            ));
8445        }
8446
8447        if self.offset == region.range.end && region.has_trailing_newline {
8448            self.offset -= 1;
8449            Some("\n")
8450        } else {
8451            let chunk = self.current_chunks.as_mut().unwrap().next()?;
8452            self.offset -= chunk.len();
8453            Some(chunk)
8454        }
8455    }
8456}
8457
8458impl<'a> Iterator for MultiBufferChunks<'a> {
8459    type Item = Chunk<'a>;
8460
8461    #[ztracing::instrument(skip_all)]
8462    fn next(&mut self) -> Option<Chunk<'a>> {
8463        if self.range.start >= self.range.end {
8464            return None;
8465        }
8466        if self.range.start == self.diff_transforms.end().0 {
8467            self.diff_transforms.next();
8468        }
8469
8470        let diff_transform_start = self.diff_transforms.start().0;
8471        let diff_transform_end = self.diff_transforms.end().0;
8472        debug_assert!(
8473            self.range.start < diff_transform_end,
8474            "{:?} < {:?} of ({1:?}..{2:?})",
8475            self.range.start,
8476            diff_transform_end,
8477            diff_transform_start
8478        );
8479
8480        let diff_transform = self.diff_transforms.item()?;
8481        match diff_transform {
8482            DiffTransform::BufferContent { .. } => {
8483                let chunk = if let Some(chunk) = &mut self.buffer_chunk {
8484                    chunk
8485                } else {
8486                    let chunk = self.next_excerpt_chunk().unwrap();
8487                    self.buffer_chunk.insert(chunk)
8488                };
8489
8490                let chunk_end = self.range.start + chunk.text.len();
8491                let diff_transform_end = diff_transform_end.min(self.range.end);
8492
8493                if diff_transform_end < chunk_end {
8494                    let split_idx = diff_transform_end - self.range.start;
8495                    let (before, after) = chunk.text.split_at(split_idx);
8496                    self.range.start = diff_transform_end;
8497                    let mask = 1u128.unbounded_shl(split_idx as u32).wrapping_sub(1);
8498                    let chars = chunk.chars & mask;
8499                    let tabs = chunk.tabs & mask;
8500                    let newlines = chunk.newlines & mask;
8501
8502                    chunk.text = after;
8503                    chunk.chars = chunk.chars >> split_idx;
8504                    chunk.tabs = chunk.tabs >> split_idx;
8505                    chunk.newlines = chunk.newlines >> split_idx;
8506
8507                    Some(Chunk {
8508                        text: before,
8509                        chars,
8510                        tabs,
8511                        newlines,
8512                        ..chunk.clone()
8513                    })
8514                } else {
8515                    self.range.start = chunk_end;
8516                    self.buffer_chunk.take()
8517                }
8518            }
8519            DiffTransform::DeletedHunk {
8520                buffer_id,
8521                base_text_byte_range,
8522                has_trailing_newline,
8523                ..
8524            } => {
8525                let base_text_start =
8526                    base_text_byte_range.start + (self.range.start - diff_transform_start);
8527                let base_text_end =
8528                    base_text_byte_range.start + (self.range.end - diff_transform_start);
8529                let base_text_end = base_text_end.min(base_text_byte_range.end);
8530
8531                let mut chunks = if let Some((_, mut chunks)) = self
8532                    .diff_base_chunks
8533                    .take()
8534                    .filter(|(id, _)| id == buffer_id)
8535                {
8536                    if chunks.range().start != base_text_start || chunks.range().end < base_text_end
8537                    {
8538                        chunks.seek(base_text_start..base_text_end);
8539                    }
8540                    chunks
8541                } else {
8542                    let base_buffer = &self.diffs.get(buffer_id)?.base_text();
8543                    base_buffer.chunks(base_text_start..base_text_end, self.language_aware)
8544                };
8545
8546                let chunk = if let Some(chunk) = chunks.next() {
8547                    self.range.start += chunk.text.len();
8548                    self.diff_base_chunks = Some((*buffer_id, chunks));
8549                    chunk
8550                } else {
8551                    debug_assert!(has_trailing_newline);
8552                    self.range.start += "\n".len();
8553                    Chunk {
8554                        text: "\n",
8555                        chars: 1u128,
8556                        newlines: 1u128,
8557                        ..Default::default()
8558                    }
8559                };
8560                Some(chunk)
8561            }
8562        }
8563    }
8564}
8565
8566impl MultiBufferBytes<'_> {
8567    fn consume(&mut self, len: usize) {
8568        self.range.start += len;
8569        self.chunk = &self.chunk[len..];
8570
8571        if !self.range.is_empty() && self.chunk.is_empty() {
8572            if let Some(chunk) = self.excerpt_bytes.as_mut().and_then(|bytes| bytes.next()) {
8573                self.chunk = chunk;
8574            } else if self.has_trailing_newline {
8575                self.has_trailing_newline = false;
8576                self.chunk = b"\n";
8577            } else {
8578                self.cursor.next();
8579                if let Some(region) = self.cursor.region() {
8580                    let mut excerpt_bytes = region.buffer.bytes_in_range(
8581                        region.buffer_range.start
8582                            ..(region.buffer_range.start + (self.range.end - region.range.start))
8583                                .min(region.buffer_range.end),
8584                    );
8585                    self.chunk = excerpt_bytes.next().unwrap_or(&[]);
8586                    self.excerpt_bytes = Some(excerpt_bytes);
8587                    self.has_trailing_newline =
8588                        region.has_trailing_newline && self.range.end >= region.range.end;
8589                    if self.chunk.is_empty() && self.has_trailing_newline {
8590                        self.has_trailing_newline = false;
8591                        self.chunk = b"\n";
8592                    }
8593                }
8594            }
8595        }
8596    }
8597}
8598
8599impl<'a> Iterator for MultiBufferBytes<'a> {
8600    type Item = &'a [u8];
8601
8602    fn next(&mut self) -> Option<Self::Item> {
8603        let chunk = self.chunk;
8604        if chunk.is_empty() {
8605            None
8606        } else {
8607            self.consume(chunk.len());
8608            Some(chunk)
8609        }
8610    }
8611}
8612
8613impl io::Read for MultiBufferBytes<'_> {
8614    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
8615        let len = cmp::min(buf.len(), self.chunk.len());
8616        buf[..len].copy_from_slice(&self.chunk[..len]);
8617        if len > 0 {
8618            self.consume(len);
8619        }
8620        Ok(len)
8621    }
8622}
8623
8624impl io::Read for ReversedMultiBufferBytes<'_> {
8625    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
8626        let len = cmp::min(buf.len(), self.chunk.len());
8627        buf[..len].copy_from_slice(&self.chunk[..len]);
8628        buf[..len].reverse();
8629        if len > 0 {
8630            self.range.end -= len;
8631            self.chunk = &self.chunk[..self.chunk.len() - len];
8632            if !self.range.is_empty()
8633                && self.chunk.is_empty()
8634                && let Some(chunk) = self.chunks.next()
8635            {
8636                self.chunk = chunk.as_bytes();
8637            }
8638        }
8639        Ok(len)
8640    }
8641}
8642
8643impl<'a> Iterator for ExcerptChunks<'a> {
8644    type Item = Chunk<'a>;
8645
8646    fn next(&mut self) -> Option<Self::Item> {
8647        if let Some(chunk) = self.content_chunks.next() {
8648            return Some(chunk);
8649        }
8650
8651        if self.has_footer {
8652            let text = "\n";
8653            let chars = 0b1;
8654            let newlines = 0b1;
8655            self.has_footer = false;
8656            return Some(Chunk {
8657                text,
8658                chars,
8659                newlines,
8660                ..Default::default()
8661            });
8662        }
8663
8664        None
8665    }
8666}
8667
8668impl ToOffset for Point {
8669    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset {
8670        snapshot.point_to_offset(*self)
8671    }
8672    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16 {
8673        snapshot.point_to_offset_utf16(*self)
8674    }
8675}
8676
8677impl ToOffset for MultiBufferOffset {
8678    #[track_caller]
8679    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset {
8680        assert!(
8681            *self <= snapshot.len(),
8682            "offset {} is greater than the snapshot.len() {}",
8683            self.0,
8684            snapshot.len().0,
8685        );
8686        *self
8687    }
8688    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16 {
8689        snapshot.offset_to_offset_utf16(*self)
8690    }
8691}
8692
8693impl ToOffset for MultiBufferOffsetUtf16 {
8694    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset {
8695        snapshot.offset_utf16_to_offset(*self)
8696    }
8697
8698    fn to_offset_utf16(&self, _snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16 {
8699        *self
8700    }
8701}
8702
8703impl ToOffset for PointUtf16 {
8704    fn to_offset<'a>(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffset {
8705        snapshot.point_utf16_to_offset(*self)
8706    }
8707    fn to_offset_utf16(&self, snapshot: &MultiBufferSnapshot) -> MultiBufferOffsetUtf16 {
8708        snapshot.point_utf16_to_offset_utf16(*self)
8709    }
8710}
8711
8712impl ToPoint for MultiBufferOffset {
8713    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
8714        snapshot.offset_to_point(*self)
8715    }
8716    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
8717        snapshot.offset_to_point_utf16(*self)
8718    }
8719}
8720
8721impl ToPoint for Point {
8722    fn to_point<'a>(&self, _: &MultiBufferSnapshot) -> Point {
8723        *self
8724    }
8725    fn to_point_utf16<'a>(&self, snapshot: &MultiBufferSnapshot) -> PointUtf16 {
8726        snapshot.point_to_point_utf16(*self)
8727    }
8728}
8729
8730impl ToPoint for PointUtf16 {
8731    fn to_point<'a>(&self, snapshot: &MultiBufferSnapshot) -> Point {
8732        snapshot.point_utf16_to_point(*self)
8733    }
8734    fn to_point_utf16<'a>(&self, _: &MultiBufferSnapshot) -> PointUtf16 {
8735        *self
8736    }
8737}
8738
8739impl From<ExcerptId> for EntityId {
8740    fn from(id: ExcerptId) -> Self {
8741        EntityId::from(id.0 as u64)
8742    }
8743}
8744
8745#[cfg(debug_assertions)]
8746pub mod debug {
8747    use super::*;
8748
8749    pub trait ToMultiBufferDebugRanges {
8750        fn to_multi_buffer_debug_ranges(
8751            &self,
8752            snapshot: &MultiBufferSnapshot,
8753        ) -> Vec<Range<MultiBufferOffset>>;
8754    }
8755
8756    impl<T: ToOffset> ToMultiBufferDebugRanges for T {
8757        fn to_multi_buffer_debug_ranges(
8758            &self,
8759            snapshot: &MultiBufferSnapshot,
8760        ) -> Vec<Range<MultiBufferOffset>> {
8761            [self.to_offset(snapshot)].to_multi_buffer_debug_ranges(snapshot)
8762        }
8763    }
8764
8765    impl<T: ToOffset> ToMultiBufferDebugRanges for Range<T> {
8766        fn to_multi_buffer_debug_ranges(
8767            &self,
8768            snapshot: &MultiBufferSnapshot,
8769        ) -> Vec<Range<MultiBufferOffset>> {
8770            [self.start.to_offset(snapshot)..self.end.to_offset(snapshot)]
8771                .to_multi_buffer_debug_ranges(snapshot)
8772        }
8773    }
8774
8775    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<T> {
8776        fn to_multi_buffer_debug_ranges(
8777            &self,
8778            snapshot: &MultiBufferSnapshot,
8779        ) -> Vec<Range<MultiBufferOffset>> {
8780            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8781        }
8782    }
8783
8784    impl<T: ToOffset> ToMultiBufferDebugRanges for Vec<Range<T>> {
8785        fn to_multi_buffer_debug_ranges(
8786            &self,
8787            snapshot: &MultiBufferSnapshot,
8788        ) -> Vec<Range<MultiBufferOffset>> {
8789            self.as_slice().to_multi_buffer_debug_ranges(snapshot)
8790        }
8791    }
8792
8793    impl<T: ToOffset> ToMultiBufferDebugRanges for [T] {
8794        fn to_multi_buffer_debug_ranges(
8795            &self,
8796            snapshot: &MultiBufferSnapshot,
8797        ) -> Vec<Range<MultiBufferOffset>> {
8798            self.iter()
8799                .map(|item| {
8800                    let offset = item.to_offset(snapshot);
8801                    offset..offset
8802                })
8803                .collect()
8804        }
8805    }
8806
8807    impl<T: ToOffset> ToMultiBufferDebugRanges for [Range<T>] {
8808        fn to_multi_buffer_debug_ranges(
8809            &self,
8810            snapshot: &MultiBufferSnapshot,
8811        ) -> Vec<Range<MultiBufferOffset>> {
8812            self.iter()
8813                .map(|range| range.start.to_offset(snapshot)..range.end.to_offset(snapshot))
8814                .collect()
8815        }
8816    }
8817}